Documentation site

[tsampazk]

Here's a list of changes for this PR:

• Added the /docs/ directory as well as .readthedocs.yaml so that https://readthedocs.org/ can generate a documentation site for the framework
• Large parts of the main README have been modified, mainly removing the "how it works" section. This section has been moved into the documentation site and overhauled (/docs/how_deepbots_works.rst)
• Added some [project] info into pyproject.toml

Right now the readthedocs documentation site targets the fork. When this PR is merged, it will be switched to target the main repo.

Things TODO:

• Add some text into the intermediate indexing pages like deepbots.supervisor.rst?
• Add some text into the pages that contain the classes for some high level explanations?
• Go through all docstrings and improve
• Add docstings to methods that don't have one
• Investigate into moving the tutorials in the documentation site, or duplicate them there somehow?
• Same for deepworlds?