Remove and update broken links in README automatically

[sarahracaj]

I would like to add a small maintenance script to this repository that automatically updates the README by detecting and removing broken links. The script helps keep the book list clean and usable without requiring manual link checks.

I reviewed the current README and implemented the following logic in the script:
• The script parses the README file and extracts all external links
• Each link is checked via an HTTP request
• Links that return errors (e.g. 404 or unreachable) are identified
• Broken links are automatically removed from the README

I also reviewed the repository structure to ensure the script fits in cleanly without affecting existing content or formatting.
The script runs independently, does not introduce additional dependencies, and does not require any restructuring of the repository.

The contribution is straightforward: adding a lightweight Python script that can be executed to automatically clean up broken links and keep the README up to date.