feat(CI): create markdown-link-checker.yml

[jbampton]

We could use this CI to check if links in markdown files are alive.

---

^ Add meaningful description above

Read the Pull Request Guidelines for more information.
In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in UPDATING.md.

[jbampton]

This needs more work but all the dead links are listed here:

https://github.com/apache/airflow/pull/12226/checks?check_run_id=1378135549

[potiuk]

We have strong preference for adding such checks in pre-commit rather than in Github Actions - because it then makes it possible to run such checks much earlier in the development process. adding new jobs/workflow in GA is heavy and it's very difficult to reproduce it locally.

We are using the fantastic https://pre-commit.com framework and we already have ~ 60 pre-commit checks added this way. I am quite sure someone has already released markdown link checker and even if not, it should be very easy to add it to the pre-commit framework.

You have all information about pre-commits here: https://github.com/apache/airflow/blob/master/STATIC_CODE_CHECKS.rst

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.