Overhaul documentation to be more beginner-friendly

[bitbrain]

The current structure/docs are not great for people just wanting to get started. There has been a lot of feedback that people find the existing docs difficult to grasp.

One recommendation was streamlit that has great docs as a point of reference. Structuring the docs like so could be very beneficial:

1. Getting started
   • Installation
   • Fundamentals
   • First Steps
2. Develop
   • Beehave internals
   • Best practices
3. API docs
   • actual API docs of beehave (built from source)
4. Tutorials
   • various specific behaviour tree tutorials
   • video tutorials (from the community)
5. Contribute