Link validation

[tesar-tech]

It would be helpful if the build process could provide warnings or errors when a link points to a non-existent resource. For example, when I use [see the docs](docs/docs-about-someting) and the docs-about-someting file doesn't exist, it would be great to receive a notification during the build instead of finding out later.

This could improve content quality by catching broken links early. for inspiration.

[tesar-tech]

Just some quick ideas:

• It can work by scanning through the generated html files and will find all the links. There will be a lot of duplicates
• It will distinguish between relative and abs links - relative are easy to check, abs to somewhere else require some time.
• File that would be stored in the bin folder that would keep the info: link, last checked, status
  • that would be helpful to not check the links always but after some period of time (different for relative/abs). All can be set by the lib.
• So: The app runs, generates the html files, link checker starts, link checker gathers all links, link checker compare these links with the links within the "db", link checker check the new links or the expired, link checker will edit the db.