Fix broken links and formatting for documentation

[melissawm]

Description

Also adds the API documentation pages to the Table of Contents so it's more discoverable.

Tests

Docs are built successfully localy.

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• I have performed a self-review of my code. For an optional AI review, add the gemini-review label.
• [N/A] I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run end-to-end tests tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[melissawm]

I'll rebase in a second.

[melissawm]

Should be good to go now!

[bvandermoon]

Were there still broken links after rebasing? @SurbhiJainUSC recently added a CI tool that checks for broken links

[melissawm]

Yes - these are internal docs that were not included in the toctrees (like the API documentation) or that had been moved. I believe you mean the linkcheck here (

maxtext/.github/workflows/check_docs_build.yml

Line 58 in 09309ff

sphinx-build -b linkcheck docs docs/_build/linkcheck -q --keep-going

) which checks for broken external links.