Update absolute RTD links to relative paths

[darisoy]

Description

This PR converts absolute ReadTheDocs links in the docs/ directory to relative paths. Previously, internal documentation links pointed to absolute URLs on maxtext.readthedocs.io/en/latest/* (or specific versioned paths). They have been updated to use relative markdown paths (e.g., ../install_maxtext.md).

This change is being made to support documentation versioning on ReadTheDocs. When a user is browsing a historical version of the documentation (such as v0.2.2), clicking an internal link that uses an absolute latest URL redirects them back to the latest branch instead of keeping them within the v0.2.2 documentation context. Using relative paths ensures that links resolve to the correct page within the same version of the documentation currently being viewed.

We updated 15 files under the docs/ directory, replacing absolute URLs with their corresponding relative paths based on their location in the directory structure.

FIXES: b/515073747

Tests

We verified this change by successfully building the documentation locally on the TPU VM.

Commands to reproduce:

cd ~/maxtext/docs
sphinx-build -b html . _build/html

The build completed successfully with no new warnings, confirming that the relative paths are correctly resolved by Sphinx.

And build-docs workflow is passing

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.
• 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.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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