Add a check for links

[SarahAlidoost]

A github workflow can be added to check all links, something like github-action-markdown-link-check.

[lukruh]

an alternative would be something like: https://github.com/IS-ENES3/Tests

[lukruh]

I used lychee instead, since that is also used to check the docs. However, checking the source files (*.md) is pretty cheap, but also misses a lot of links that are created during build process. And I already found some cases like moved assets, that are reported when checking the built *.html files but not in the markdown source. Checking the final static page, requires a ruby installation and the jekyll build step.

My suggestion would be to create 2 different actions to catch as many broken links as possible but also don't waste resources:

• check changed source files on every PR
• build website and check generated urls once a week