tox -e docs warnings need to be cleaned up

[n2ygk]

Describe the bug

A number of warnings are logged by the docs build step:

docs: commands[0] /Users/ac45/src/django-oauth-toolkit/docs> make html
sphinx-build -b html -d _build/doctrees   . _build/html
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/sphinx/util/docutils.py:49: DeprecationWarning: distutils Version classes are deprecated. Use packaging.version instead.
  __version_info__ = tuple(LooseVersion(docutils.__version__).version)
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/sphinx/util/rst.py:58: DeprecationWarning: 'environmentfilter' is renamed to 'pass_environment', the old name will be removed in Jinja 3.1.
  def heading(env: Environment, text: str, level: int = 1) -> str:
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/pkg_resources/__init__.py:121: DeprecationWarning: pkg_resources is deprecated as an API
  warnings.warn("pkg_resources is deprecated as an API", DeprecationWarning)
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/pkg_resources/__init__.py:2870: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('sphinxcontrib')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/pkg_resources/__init__.py:2870: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('sphinxcontrib')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/pkg_resources/__init__.py:2870: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('sphinxcontrib')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/pkg_resources/__init__.py:2870: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('sphinxcontrib')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
Running Sphinx v2.4.5
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/sphinx/jinja2glue.py:106: DeprecationWarning: 'contextfunction' is renamed to 'pass_context', the old name will be removed in Jinja 3.1.
  def warning(context: Dict, message: str, *args: Any, **kwargs: Any) -> str:
WARNING: while setting up extension rfc: role 'rfc' is already registered, it will be overridden
loading pickled environment... done
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/sphinx/jinja2glue.py:184: DeprecationWarning: 'contextfunction' is renamed to 'pass_context', the old name will be removed in Jinja 3.1.
  self.environment.globals['debug'] = contextfunction(pformat)
/Users/ac45/src/django-oauth-toolkit/.tox/docs/lib/python3.8/site-packages/sphinx/jinja2glue.py:186: DeprecationWarning: 'contextfunction' is renamed to 'pass_context', the old name will be removed in Jinja 3.1.
  self.environment.globals['accesskey'] = contextfunction(accesskey)
loading intersphinx inventory from https://docs.python.org/3.6/objects.inv...
loading intersphinx inventory from http://django.readthedocs.org/en/latest/objects.inv...
intersphinx inventory has moved: http://django.readthedocs.org/en/latest/objects.inv -> https://django.readthedocs.io/en/latest/objects.inv
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 30 source files that are out of date
updating environment: [config changed ('version')] 30 added, 0 changed, 0 removed
reading sources... [100%] views/views                                                                                                              
../CHANGELOG.md:3: WARNING: Duplicate explicit target name: "tutorial".
../CHANGELOG.md:3: WARNING: Duplicate explicit target name: "tutorial".
../CHANGELOG.md:3: WARNING: Duplicate explicit target name: "tutorial".
/Users/ac45/src/django-oauth-toolkit/docs/contributing.rst:261: WARNING: Unexpected indentation.
/Users/ac45/src/django-oauth-toolkit/docs/contributing.rst:262: WARNING: Block quote ends without a blank line; unexpected unindent.
/Users/ac45/src/django-oauth-toolkit/oauth2_provider/models.py:docstring of oauth2_provider.models.AbstractIDToken:1: WARNING: Unknown interpreted text role "openid".
/Users/ac45/src/django-oauth-toolkit/docs/oidc.rst:292: WARNING: Unexpected indentation.
/Users/ac45/src/django-oauth-toolkit/docs/oidc.rst:336: WARNING: Unexpected indentation.
/Users/ac45/src/django-oauth-toolkit/docs/settings.rst:348: WARNING: Title underline too short.

OIDC_RP_INITIATED_LOGOUT_ENABLED
~~~~~~~~~~~~~~~~~~~~~~~~
/Users/ac45/src/django-oauth-toolkit/docs/settings.rst:348: WARNING: Title underline too short.

OIDC_RP_INITIATED_LOGOUT_ENABLED
~~~~~~~~~~~~~~~~~~~~~~~~
/Users/ac45/src/django-oauth-toolkit/docs/settings.rst:363: WARNING: Title underline too short.

OIDC_RP_INITIATED_LOGOUT_STRICT_REDIRECT_URIS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/ac45/src/django-oauth-toolkit/docs/settings.rst:363: WARNING: Title underline too short.

OIDC_RP_INITIATED_LOGOUT_STRICT_REDIRECT_URIS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/ac45/src/django-oauth-toolkit/docs/settings.rst:369: WARNING: Title underline too short.

OIDC_RP_INITIATED_LOGOUT_ACCEPT_EXPIRED_TOKENS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/ac45/src/django-oauth-toolkit/docs/settings.rst:369: WARNING: Title underline too short.

OIDC_RP_INITIATED_LOGOUT_ACCEPT_EXPIRED_TOKENS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:2: WARNING: duplicate object description of oauth2_provider.views.mixins, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:5: WARNING: duplicate object description of oauth2_provider.views.mixins.ClientProtectedResourceMixin, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:13: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:31: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.authenticate_client, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:40: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_authorization_response, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:53: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_revocation_response, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:62: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_token_response, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:70: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_userinfo_response, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:79: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.error_response, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:87: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_oauthlib_backend_class, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:94: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_oauthlib_core, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:102: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_scopes, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:109: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_server, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:117: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_server_class, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:124: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_validator_class, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:131: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.validate_authorization_request, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:139: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.verify_request, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:147: WARNING: duplicate object description of oauth2_provider.views.mixins.OIDCLogoutOnlyMixin, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:158: WARNING: duplicate object description of oauth2_provider.views.mixins.OIDCOnlyMixin, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:169: WARNING: duplicate object description of oauth2_provider.views.mixins.ProtectedResourceMixin, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:176: WARNING: duplicate object description of oauth2_provider.views.mixins.ReadWriteScopedResourceMixin, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:182: WARNING: duplicate object description of oauth2_provider.views.mixins.ReadWriteScopedResourceMixin.get_scopes, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:190: WARNING: duplicate object description of oauth2_provider.views.mixins.ScopedResourceMixin, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/details.rst:196: WARNING: duplicate object description of oauth2_provider.views.mixins.ScopedResourceMixin.get_scopes, other instance in views/mixins, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:2: WARNING: duplicate object description of oauth2_provider.views.mixins, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:5: WARNING: duplicate object description of oauth2_provider.views.mixins.ClientProtectedResourceMixin, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:13: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:31: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.authenticate_client, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:40: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_authorization_response, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:53: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_revocation_response, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:62: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_token_response, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:70: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.create_userinfo_response, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:79: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.error_response, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:87: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_oauthlib_backend_class, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:94: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_oauthlib_core, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:102: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_scopes, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:109: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_server, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:117: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_server_class, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:124: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.get_validator_class, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:131: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.validate_authorization_request, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:139: WARNING: duplicate object description of oauth2_provider.views.mixins.OAuthLibMixin.verify_request, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:147: WARNING: duplicate object description of oauth2_provider.views.mixins.OIDCLogoutOnlyMixin, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:158: WARNING: duplicate object description of oauth2_provider.views.mixins.OIDCOnlyMixin, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:169: WARNING: duplicate object description of oauth2_provider.views.mixins.ProtectedResourceMixin, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:176: WARNING: duplicate object description of oauth2_provider.views.mixins.ReadWriteScopedResourceMixin, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:182: WARNING: duplicate object description of oauth2_provider.views.mixins.ReadWriteScopedResourceMixin.get_scopes, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:190: WARNING: duplicate object description of oauth2_provider.views.mixins.ScopedResourceMixin, other instance in views/details, use :noindex: for one of them
/Users/ac45/src/django-oauth-toolkit/docs/views/mixins.rst:196: WARNING: duplicate object description of oauth2_provider.views.mixins.ScopedResourceMixin.get_scopes, other instance in views/details, use :noindex: for one of them
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing/Users/ac45/src/django-oauth-toolkit/docs/management_commands.rst:37: WARNING: Could not lex literal_block as "sh". Highlighting skipped.   
 output... [100%] views/views                                                                                                               
generating indices...  genindex py-modindexdone
writing additional pages...  searchdone
copying images... [100%] tutorial/celery+add.png                                                                                                   
copying static files... ... done
copying extra files... done
dumping search index in English (code: en)... done
dumping object inventory... done
build succeeded, 64 warnings.

To Reproduce

tox -e docs

Expected behavior

No warnings

Version

• I have tested with the latest published release and it's still a problem.
• I have tested with the master branch and it's still a problem.

Additional context

Need to do some housekeeping to clean up these various minor errors.