rubocop: Try out rubocop-md for linting the code in our docs

[issyl0]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

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• Maybe we can tidy up the code in our docs using this RuboCop extension to lint codeblocks in Markdown?

[issyl0]

cannot load such file -- rubocop-md Yes, I'm also getting this locally. But brew style on this branch initially runs install_bundler_gems, because of the Gemfile changes, and it does install the gem, so it should work? What am I missing? 🤔

[issyl0]

I figured it out! I was missing brew vendor-gems.

[apainintheneck]

I'm kind of surprised that the number of offenses is so low.

[issyl0]

Oh, CI passing isn't representative, I've not got this working yet, but locally there are still 60-odd problems.

[MikeMcQuaid]

Looking good so far, thanks @issyl0!

[MikeMcQuaid]

Looking great so far, thanks @issyl0!

[MikeMcQuaid]

Looks pretty good, a few nits, thanks @issyl0!

[MikeMcQuaid]

Looks good! One suggestion, non-blocking.