Add CLI documentation

[yeoldegrove]

What this PR does / why we need it:

This adds auto-generated CLI documentation via sphinx.
It also adds some missing help texts to CLI.
Finally, it adds some style ;)

Note for reviewer:
Needs #271 merged first.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.88%. Comparing base (f420f50) to head (0569798).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #301      +/-   ##
==========================================
+ Coverage   90.83%   90.88%   +0.05%     
==========================================
  Files          45       45              
  Lines        2269     2282      +13     
==========================================
+ Hits         2061     2074      +13     
  Misses        208      208              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[ByteOtter]

I always like more documentation, sphinx is nice for code docs like this and we can integrate it with #gardenlinux/gardenlinux#4329