[FEATURE REQUEST] Add a way to check for dead links about academy

[runningdeveloper]

Hi here is a github action that might help https://github.com/lycheeverse/lychee-action

[darigovresearch]

@runningdeveloper thanks for raising this potential solution. @chrismclarke what do you think?

[chrismclarke]

I really like the idea of using a github action, that way we can set it up as a cron task to check regularly (e.g. if something has been moved) instead of during deployment (which doesn't happen very often).

I've just opened up a PR to test:
#142

You can see the full output from the run here:
https://github.com/ONEARMY/academy/runs/3786194423?check_suite_focus=true

It also created an issue from the report here:
#141

I'm guessing it needs some extra configuration because it's showing a lot of file errors which I don't think are accurate, but maybe someone else can confirm/test a bit more? Feel free to make any updates to the PR if wanting to check/test

I also saw this action: https://github.com/gaurav-nelson/github-action-markdown-link-check
Not sure if there's much difference, happy with whatever works myself

[chrismclarke]

I just updated the link checker to run after the site is built (to try and fix incorrect asset paths) and the output is better but still seems to report a few false-positives. What do you think @darigovresearch @runningdeveloper ?

Second check output: #143

[chrismclarke]

Run 3: #145

I tested locally using the tool from command line and actually the output was looking much nicer (only a couple broken links), so I just tried bumping the version to latest (docs were outdated) and this time looking better again. I also reverted the build step as appears to be working from raw markdown which is a bit faster

[darigovresearch]

@chrismclarke nice work. GitHub actions seems like a good approach. Showing the error page & the link that is not working is really helpful!