chore: simplify the api docs workflow

[dougch]

Issues:

Resolves: none

Description of changes:

The doc.go tool requires being run from the util/ directory with explicit --config and --out flags. This makes the GitHub Pages workflow brittle and the tool unusable from the repo root.

as a reminder, the final doc URL: https://aws.github.io/aws-lc/api/headers.html

Changes:

• doc.go auto-locates its config file via runtime.Caller(0) — no more CWD dependency
• Add OutputDirectory field to doc.config so output path lives in config, not the CLI
• Resolve BaseDirectory and OutputDirectory relative to config file location
• Auto-create output directory
• Fix doc.css copy path to be config-relative

Call-outs:

• This workflow only triggers publish on push to main, but does a validation of comments on PRs.
• workflow_dispatch can be used to test manually after merge
• Backwards compatible: --config and --out flags still work as overrides

Testing:

Run locally: go run util/doc.go from repo root — generates docs in pages-output/, with the main entrypoint pages-output/headers.html.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.20%. Comparing base (3ab37a8) to head (253dc4f).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #3186    +/-   ##
========================================
  Coverage   78.19%   78.20%            
========================================
  Files         695      695            
  Lines      124086   124192   +106     
  Branches    17222    17246    +24     
========================================
+ Hits        97035    97129    +94     
- Misses      26129    26142    +13     
+ Partials      922      921     -1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

🔒 Security Review — View Report

Please review before merging.