Improve the Linkchecker

[bemayr]

Problem Description

The link checker in its current version works and really improves the user experience, but it could be enhanced even more using 11ty checks.

Resources towards a solution

• [ ] https://dev.to/modern-web/introducing-check-html-links-no-more-bad-links-1jdg
• [ ] https://www.npmjs.com/package/eleventy-plugin-broken-links

[bemayr]

superseded by #117