Documentation

[trappitsch]

With the controller_cli and the controller GUI version, the documentation as it is handled now just via readme files in the respective folders is getting clunky.
I started creating a website in the docs folder (generated by sphinx and currently deployed as a github page). All readme documentation should be transported over there.

One issue with github pages is, that I'm unclear on how versioning will work. If it is important to keep old versions, the docs might have to switch over to readthedocs.

The main readme on the page should in the future:

• give details on the project
• explain what modules are available (hardware, firmware, cli, gui, ...) and link to the correct page in the docs
• explain how versioning works
• status badges