Add wiki link checker

Describe the feature

Check wiki links for broken links.

Is there a prototype?

markdown-link-check says it can check links in markdown pages. And it gives instructions on how to do it in a Gitlab pipeline.

Describe the feature in more detail

It's easy to mess up links in wiki pages so it would be really nice to have something check the links for us. Ideally we would run this in the pipeline and get notified of all the broken links.