ci(markdown): re-enable markdown linting (see #284)

[jayjayjpg]

What it does

This reenables the markdown linting step in CI after merging #284

Related Issue(s)

Sources

[amyrlam]

lgtm. Are any of these rules no value added? https://github.com/ember-learn/ember-blog/blob/master/.markdownlint.json

Some of them I added such as no-trailing-punctuation, no-trailing-spaces, because it makes the diffs easier to review.

[jayjayjpg]

@amyrlam I think the rules that we have so far are useful! I think that switching on the rules requires them to to be set to true in the config file, unless they're already set to true in the default config of the linter, but I haven't checked yet, how the default config actually looks like

I can take another look into it though or as you suggested, we can also brainstorm with the Times team, to see which rules make most sense for us

[amyrlam]

Oh yeah, sorry those are false haha 🙈

[amyrlam]

down to merge it in, and if the rules are proving cumbersome, can iterate?

[jayjayjpg]

down to merge it in, and if the rules are proving cumbersome, can iterate?

@amyrlam Yes, sounds good ✨