Central place for documenting the different roles, creating and using them.

We have some scattered information about roles/permissions so far. We could have one document specifically about it. We seem to get questions about these details so it makes sense to add the most common cases to a single prominent document.

Should include the technical details as well as the manual/glossary has another view (that could perhaps be improved as well).

Can link to application-permissions.md or be part of it?

Include details such as
- how to create each kind of user (db, CLI, API, UI)
- what is the intent of each user type (i.e. handler is the operative person acting whereas owner is a organizational owner of the concepts)
- handler/reviewer are dynamic roles based on the applications
- use of technical users (like the bots are)
- how to limit API-keys should be discussed somewhere

Start by reviewing application-permissions.md and the existing manual/glossary material, then locate the scattered information about roles and permissions. Done means a prominent document covers user creation through the database, CLI, API, and UI, explains each role and technical users, discusses API-key limits, and links to or incorporates the existing material.

Written by the indexing model from the issue text.