Modify pull request template

Author: tjrana

.github/PULL_REQUEST_TEMPLATE.md

@@ -4,8 +4,8 @@ fill out the following questions to make it easier for us to review your
 changes.
 -->
 
-What changes are made in this PR? What problem does it solve?
--------------------------------------------------------------
+What does this PR change? What problem does it solve?
+-----------------------------------------------------
 
 <!--
 Describe the changes and their purpose here, as detailed as needed.
@@ -25,17 +25,15 @@ Checklist
 ---------
 
 <!--
-Fill out this checklist by replacing [ ] with [x].
-
 You do not need to check all the boxes below all at once. Feel free to take
 your time and add more commits. If you're done and ready for review, please
-check the last box.
+check the last box. Enable a checkbox by replacing [ ] with [x].
 -->
 
 - [ ] I have read the [contribution guidelines](https://github.com/restic/restic/blob/master/CONTRIBUTING.md#providing-patches).
-- [ ] I have [enabled maintainer edits](https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/allowing-changes-to-a-pull-request-branch-created-from-a-fork) for this PR.
-- [ ] I have added tests for all code changes in this PR.
-- [ ] I have added documentation for the those changes (in the manual).
+- [ ] I have [enabled maintainer edits](https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/allowing-changes-to-a-pull-request-branch-created-from-a-fork).
+- [ ] I have added tests for all code changes.
+- [ ] I have added documentation for relevant changes (in the manual).
 - [ ] There's a new file in `changelog/unreleased/` that describes the changes for our users (see [template](https://github.com/restic/restic/blob/master/changelog/TEMPLATE)).
 - [ ] I have run `gofmt` on the code in all commits.
 - [ ] All commit messages are formatted in the same style as [the other commits in the repo](https://github.com/restic/restic/blob/master/CONTRIBUTING.md#git-commits).