Lint markdown in PRs

[gonX]

Lints markdown with markdownlint-cli with the GitHub action nosborn/github-action-markdown-cli.

Uses my local fork until a PR is merged that we need: nosborn/github-action-markdown-cli#64

Notes

• Fragments to other pages does not seem to be verified (e.g. {% link /index.md %}#myid %}) less of a concern with #76
• Code blocks after <ol>'s are not linted for indentation. We can't reasonably lint for this even with a custom rule so I've tried to make sure code blocks are indented correctly with this PR.

[gonX]

~~Add how to lint to README: markdownlint --ignore "vendor/" --ignore _includes/tablets.md --ignore _data/plugin-repository/ . 2>&1 | less~~

Added in f1e76ca4b044

Integrating these ignores into the .markdownlint conf is also an option

Doesn't seem like we can actually configure this

[gonX]

Rebased to work with the new Jekyll 4.x deployment

[X9VoiD]

Worth considering if we want to add markdown linting via docker image to avoid pulling node/npm:

docker run -v $PWD:/workdir ghcr.io/igorshubovych/markdownlint-cli:latest "*.md"

example taken from https://github.com/igorshubovych/markdownlint-cli

[gonX]

Worth considering if we want to add markdown linting via docker image to avoid pulling node/npm:

docker run -v $PWD:/workdir ghcr.io/igorshubovych/markdownlint-cli:latest "*.md"

example taken from https://github.com/igorshubovych/markdownlint-cli

Nice, will test which is faster before merging.

[X9VoiD]

I think its current state can be merged now as-is, but I'm leaving that decision to you @gonX since I'm not sure if you still have some other plans for this PR. Fwiw, the docker thing can just be done on a later PR as it doesn't change anything functionally.

[gonX]

Ok, makes sense