docs(#198): sync README and RTD index content for AboutCode overview and TOC

[satyajeetch1991]

Summary

This PR addresses issue #198 by updating and synchronizing the "What is AboutCode?" and "Projects" sections across the GitHub README.md and ReadTheDocs index.rst. It ensures users see consistent and accurate documentation in both locations.

Changes Made

• 🔁 Revised the README with improved explanation and cleaned project listings
• 🧭 Updated docs/index.rst to mirror README overview and TOC structure
• 🤖 Added .github/workflows/sync-readme-to-rst.yml GitHub Action to automate Markdown to reStructuredText syncing (if needed in future)
• 🧪 Verified Sphinx builds and doc8 styling checks pass locally

Fixes

Fixes #198

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✅ Checklist

• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass (Sphinx build + doc8 style check) ✔️
• Commits are in a uniquely-named feature branch and have no merge conflicts 📁
• Added GitHub Action workflow file for syncing future README updates if required

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If any CI tests fail, click the ❌ icon to expand the logs and identify the problem. Most failures are either doc8 formatting issues or Sphinx warnings. Feel free to ask for help if needed.

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🔏 Sign-Off

Contributed by @satyajeetch1991 as part of improving project documentation consistency.