Add automated Markdown link checker workflow

[alok-108]

This PR adds a GitHub Actions workflow to automatically find broken links in Markdown files, as discussed in #295.

What it does

• Runs when .md files are pushed to main or in a pull request – checks only changed files.
• A weekly scheduled job checks all files.
• Uses markdown-link-check with a custom config.

Config highlights

• Retries failed links 3 times (handles temporary network issues).
• Accepts HTTP 429 as “alive” to avoid rate‑limit false alarms.
• Skips domains that often fail or rate‑limit: web.archive.org, yewtu.be, gnu.org, and GitHub issue/PR links.
• Tested on a feature branch – broken links are caught, ignored links are properly skipped.

Closes #295

[github-actions]

Hi @alok-108,

⚠️ Potential typos found in your pull request:

• 📄 ./docs/wiki/research/history-expiry/history-expiry.md (line(s) 37,39):
  1. ❌ bitmask
• 📄 ./docs/wiki/research/history-expiry/history-expiry.md (line(s) 37,39):
  1. ❌ bitmask
• 📄 ./docs/wiki/CL/cl-networking.md (line(s) 251):
  1. ❌ decrypt

ℹ️ How to fix this error:

1. If these are actual typos:

   • Open the files at the specified line numbers and fix them

2. If these are names or one-off nouns:

   • Wrap them in <name> tags
   • Example: <name>Alex Pereira</name>
   • Use this for people's names or unique terms that appear rarely

3. If these are valid terms:

   • Add them to wordlist.txt (one word per line)
   • Terms must be plain text without spaces/special chars
   • The list is case-insensitive

4. If these are code terms:

   • Wrap them in backticks (`) in your markdown

ℹ️ Checking for typos locally

1. Install aspell for your platform
2. Navigate to project root and run:

for f in **/*.md ; do echo $f ; aspell --lang=en_US --mode=markdown --home-dir=. --personal=wordlist.txt --ignore-case=true --camel-case --add-sgml-skip nospellcheck list < $f | sort | uniq -c ; done

Learn more about wordlist format

[alok-108]

Hi @raxhvl @taxmeifyoucan! I've opened a PR for automated link validation (#295). It's tested on a feature branch and handles all discussed edge cases (web.archive, 429, etc.). Looking forward to your feedback! 🚀