Optimized Sphinx Configuration for Improved Documentation & Code Linking

[SophiaLi20]

This PR improves the Sphinx documentation configuration by:

• Enhancing readability & maintainability with structured sections.
• Optimizing performance (reducing redundant sys.path.insert() calls).
• Strengthening error handling in linkcode_resolve().
• Making GitHub source links more reliable & cross-platform friendly.

Key Improvements

• Better Structure → Grouped settings logically & added meaningful comments.
• Cross-Platform Safe → Used os.path.join() & os.path.relpath().
• More Reliable GitHub Linking → Handles class, method, & module-level linking.
• Robust Error Handling → Prevents crashes when attributes are missing.

Next Steps
Run make clean && make html to test the build.
Let me know if there’s anything that could be improved further! Open to feedback and suggestions.

Looking forward to you thoughts!