Consider disabling link check CI

[SamWhited]

I wonder if it would make sense to disable the link check in CI? I've never seen it pass, so it's likely just hammering sites with pings for no reason since it's always red and then PRs get merged anyways.

Alternatively, if there's a way to make it only run on changed files maybe that would limit the scope a bit and make it more likely to find useful breakages and less likely to be broken from the usual assortment of random stuff? (and then maybe only run it globally on request, or when tagging a release or something where we can baby sit it and double check the results?)

Assuming the internet is reliable and stable is never going to get you far, IMO :)

[Swiftb0y]

Well, its to have a manual thats full of dead links. The link check is there to tell us when a link is dead. It usually gets ignored because it doesn't happen very often that somebody actually fixes these links. Asking the author of an unrelated change to fix a link is not sensible. Running the linkcheck globally on every PR instead of only on changed lines and/or periodically would make more sense. PRs are welcome.

[acolombier]

I somewhat agree with @SamWhited. I don't think it makes sense to check links on a PR since this checks has nothing to do with changes 99% of the time. The remaining 1%, since this is a URL that is being added, the reviewer will always check what it is about anyway before approving/merging the PR.

That being said, I think having a manual full of dead link would be a pretty poor experience, so I agree with the suggestion of adding a periodical check instead of PR-based. This would also allow us to check multiple live version of the doc and actively fix/remove links from other Mixxx version.