Add remark-lint for a markdown fixer

[blyoa]

Closes #1211

This PR added remark-lint for a markdown fixer.

This feature is already reported in #1211, and this PR was based on code proposed by @dirkroorda there.

[w0rp]

Looks good to me. Could you document the new options? Sorry for the delay.

[blyoa]

Thank you for the review, and I'm sorry for the delay.
This PR does not introduce any new option and uses the same options of remark-lint for a linter. I referenced options of eslint, which works as both a linter and a fixer, and I did not add any description, but should I add it?

[stale]

This pull request has been automatically marked as stale because it has not been updated recently. Make sure to write tests and document your changes. See :help ale-dev for information on writing tests.
If your pull request is good to merge, bother w0rp or another maintainer again, and get them to merge it.

[dbellavista]

Hi @w0rp ! I was waiting for this merge request to be completed, I took a look at :help ale-dev but I think everything is in order. The documentation is missing because the tool is already documented and listed as supported, so I can't really find a place where to document this.

If @blyoa is not available to make the required changes I could replicate and fix the merge request

[w0rp]

Cheers! 🍻

[w0rp]

Nevermind the stale bot. I'm actually using it to get pull requests merged faster by automating it poking people for responses and getting some answers back.