Add basic organization user docs

What does this MR do and why?

As we start to have more of the organization views built out this MR adds basic docs for the currently built views. It also documents the ui_for_organizations feature flag.

Note that most of these views are still using mock data while we wait for APIs to be available so they may not function 100% correctly.

How to set up and validate locally

1. Open Rails console
   • bin/rails console
2. Enable the feature flag
   • Feature.enable(:ui_for_organizations)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.