refactor: improve option definitions

[paul-soporan]

I've experimented with using the option descriptions inside Yarn's CLI docs, but the option definitions have a few problems:

• The options with descriptions weren't excluded from the usage.
• The options field also included options without descriptions.
• The options[].definition field was simply a join rather than a full definition (which should also include the arity - -p,--package #0)

Also, the descriptions weren't formatted as markdown(ish) on the Command help page (useful to highlight backticks).

A small proof of concept of what the option descriptions could look like inside Yarn's CLI docs (after this PR is merged):

[arcanis]

Released in 2.6.1 👍