Fix local mdBook serving issues and expand learning resources

[anshulbadhani]

Summary

This PR fixes issues that prevented mdbook serve from working on a fresh clone
and expands the learning resources section.

Changes

• Fixed local mdbook serve errors:
  • Removed unsupported mdBook configuration
  • Updated outdated Font Awesome icon usage
• Added and reorganized learning resources for:
  • Python
  • AI / Machine Learning
• Grouped resources into clearer sections to improve discoverability

Motivation

While setting up the project locally as a new contributor, mdbook serve failed
due to undocumented assumptions in the configuration and theme. These fixes make
local development work out of the box.

The resource updates aim to provide better structure and more options for learners,
without removing existing content.

Notes

All changes were tested locally using mdbook serve.