add linting for docs markdown content #13

@earl-warren is this the best approach, or would it be better to create a separate action for linting? I guess a separate action would give better at-a-glance insight into what fails from the PR page.

Each run step shows with its name and FWIW I find the separation good enough. What is disturbing is that sometimes the output of a step is found in another. Other than this it is ok.

I initially tried that and then realized it is more difficult to work with. But that's a matter of personal preference, I think. At least with a sequence of run that very much look like a shell script it is easier to figure out what's going on without any Forgejo Action expertise.

What?

Prettier wants to remove the whitespace inside the code tags. It wanted to on the website repo too, it's not to do with the new config. It was just never run on the whole repo before, only on new commits. I thought this seemed like a good time to run it on the whole repo.

Sure. It's just a bit awkward since this is the only change that's not introducing the linter itself. We could make a separate commit with this and merge it first. It should be fine as is, though.

I felt that whilst adding the linter was a good time to lint everything, but if you think it should be a separate commit I'm happy either way.

For what it's worth there are a bunch of other lint changes it might be good to make at some point. In particular, I disabled remark-lint-no-undefined-references because the code is full of unescaped square brackets that aren't meant to be links. Ideally I think it should be re-enabled and they should all be escaped, but that should definitely be a commit of its own because it's a ton of changes.