docs: auto-generate docs

[pendo324]

Issue #, if available:

Description of changes:

• Add finch gen-docs generate command, which can be used to generate documentation
  • This actually runs all of the commands, so a finch vm needs to be running
    • This is because many of the commands shell out to nerdctl inside of a Linux VM, so simply leveraging cobra's built-in documentation generation won't work
    • Actually running the commands and then parsing the output into a markdown file is... kinda hacky, so this might break from time to time
• This only works for top-level nerdctl commands right now, because those are the only commands that finch "knows" about. Meaning, while finch volume create is a command, with it's own usage information, it won't have a page here. The doc for finch volume does reference its subcommands, however.

Testing done:

• TODO

  • unit tests

• I've reviewed the guidance in CONTRIBUTING.md

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ningziwen]

Good to have a gen-docs-no-diff in ci.
Similar to

finch/.github/workflows/ci.yaml

Line 37 in e21ae83

- run: git diff --exit-code

[pendo324]

The nature of this code makes it very hard to add more tests than what I've added in the latest commit. It both modifies os.Stdout, AND is recursive. I tried mocking out the scenario where there's a parent command and it does not seem worth the effort since this is not really a critical command anyway.

[vsiravar]

Nice!

[weikequ]

Left some small comments. Thanks for the good work!

[weikequ]

🚀

[pendo324]

Skipping CI e2e tests take a long time and it's passed previously (these changes are unrelated to e2e tests)