feature: Print long help text for options

[ilyagr]

This fixes #20.

I separated this from #22 since there is a bit more logic here. The first commit is shared with #22, since test changes are confusing without that commit. I will rebase one of the PRs if you merge the other (unless you do it).

This duplicates janstarke#2, but is rebased onto this repo's main branch.

[ConnorGray]

This is great, thank you @ilyagr for these nice QoL contributions! 🧹 🙂

[ilyagr]

Thank you very much for merging this, #22, as well as starting and maintaining this project! I'm very glad to see that it is not abandoned.

I use clap-markdown to make https://martinvonz.github.io/jj/prerelease/cli-reference/, which is possible because of this project, and should improve significantly once the new version of clap-markdown is released. We'll finally be able to make the Warning in the beginning less scary.

[ilyagr]

Here's the diff: https://github.com/martinvonz/jj/pull/3891/files#diff-241a36d22079376383ba2fbdd9921ba5b1492f2ce080a8b965373b52cf92656e. I'm just sharing it because I'm quite happy about it. It might take me a bit to actually merge that PR.

[ConnorGray]

That's awesome @ilyagr, I'm glad to see the new version is improving things for you! 🙂

Please let me know if there are any other features that would be useful to you!

As a sneak peak for you as well: I'm currently working on a small overhaul to clap-markdown to use a Markdown AST representation internally instead of a raw string builder, which should make it much easier to add more user-customizable behavior to clap-markdown in a structured way.

[gibfahn]

Just came here to work out how to fix this, and it's already fixed 🎉 . Thanks folks for making this library better.