Add markdown link checker action

[m4ns0ur]

Similar to link checker action in Massa docs: https://github.com/massalabs/docs/pull/157/files/d3499d290c95240b4720aea10c3e32a2bd20b903 Fixes: #3586

• [ ] document all added functions
• [ ] try in sandbox /simulation/labnet
  • [ ] if part of node-launch, checked using the resync_check flag
• [ ] unit tests on the added/changed features
  • [ ] make tests compile
  • [ ] make tests pass
• [ ] add logs allowing easy debugging in case the changes caused problems
• [ ] if the API has changed, update the API specification