Sphinx setup for MCGrad

[TaXxER]

Add Sphinx Documentation Setup

Summary

This PR adds Sphinx-based API documentation for MCGrad, following the same pattern as the Ax repository. The project now uses a dual documentation system:

1. Docusaurus (User Guide) - Hosted on GitHub Pages at https://facebookincubator.github.io/MCGrad/
2. Sphinx (API Reference) - Ready for ReadTheDocs hosting at https://mcgrad.readthedocs.io/

This approach provides:

• Auto-generated API docs from Python docstrings (no manual maintenance)
• Professional documentation with type hints, cross-references, and search
• Versioned documentation automatically built for each Git tag (via ReadTheDocs)

What Changed

New Files

• sphinx/ - Complete Sphinx documentation setup

  • source/conf.py - Sphinx configuration with autodoc, Napoleon (Google-style docstrings), type hints
  • source/index.rst - Main documentation entry point
  • source/api/*.rst - Simple RST files for each module (using automodule directive)
  • Makefile - Build commands
  • requirements.txt - Sphinx dependencies
  • README.md - Documentation for working with Sphinx

• .readthedocs.yaml - ReadTheDocs configuration (auto-detected when importing project)

• scripts/test_docs.sh - Automated test script for both Sphinx and Docusaurus builds

• DOCUMENTATION_TESTING.md - Comprehensive guide for testing and validating documentation

Modified Files

• .github/workflows/main.yaml - Added sphinx job to build and validate Sphinx docs on every push

• website/docusaurus.config.js - Added "API Reference" link in navbar pointing to ReadTheDocs

• README.md - Updated documentation section to explain dual documentation system

• .gitignore - Added Sphinx build artifacts (sphinx/build/, *.doctrees, .buildinfo)

Testing the Documentation

Quick Test (Both Systems)

Run the automated test script:

./scripts/test_docs.sh

[meta-codesync]

@TaXxER has imported this pull request. If you are a Meta employee, you can view this in D88387259.