Add test fixtures for line breaks support.

[kdeldycke]

This is a proposal to allow for line breaks in both link titles and descriptions.

I updated the fixtures to demonstrate the feature I look forward to implement. Of course tests are failing. But if the community validates that format, I can update that PR to implement the corresponding rules.

[sindresorhus]

Thanks for the suggestion, but that's intentional. Forced-linebreaks are contributor-hostile. A single word change could potentially force a user to manually have to reflow lines, which is especially painful when contributing in the GitHub web UI editor.

[kdeldycke]

OK, I understand your point of view. I was also concerned about that one too.

In the last few weeks I tried not only to automate linting by the way of GitHub Actions, but also autofix and format Mardown. Which is a featured requested at #103.

I played with tools like pandoc and cmark, and I think we can delegate the hard work of reflowing the content to these CLIs.

My goal is to deploy a forgiving workflow, in which contributors will not have to bother reflowing content. An auto-formatting commit might be applied to any new PR or change. We're not that far from a dream setup in which neither contributors or maintainers will not have to worry too much about nitpicking! 😉

Anyway, no offense taken closing that PR. I'll keep applying the current rules and work towards auto-reflow on the side. Thanks @sindresorhus for the reply! 👍