Admin docs improvement

[anbraten]

The latest version of the docs makes it quite hard for an admin to walk-through. It would be great to have some more guidance as an admin how to setup a basic instance. With links at the end of the pages to continue reading like: As the next step you need to decided on a [database](...).

Suggestions for this:

• add some getting started page for the admin section
• sort the folders somehow like:
  • choose a deployment way (docker-compose, k8s, ...)
  • choose a database
  • setup a forge connection
  • add your first agent
  • reverse proxy
  • advanced stuff (addons, autoscaler, prometheus, secrets encryption, ...)