Add API section to the docs website

[mkcp]

Is your feature request related to a problem? Please describe.

With the ongoing packager2 migration, Zarf is changing to better support users directly invoking its API rather than just using the CLI.

Describe the behavior you'd like

CLI / API docs on the website provide guidance for users on the core functionality that those utilizing Zarf as a library will benefit from. The goal is to offer a "paved road" to follow with examples and notes (where appropriate).

Describe alternatives you've considered

Godocs and doccomments form another part of the puzzle and should be complete when possible. It's ok if there's a bit of duplication between the website and doccomments, because the website is intended to show common and expected usecases.