Set up documentation tool for install & configuration guides

[Kisgus]

Decide on tool

• [x] Decide on which tool to use such as readthedocs / 0x documentation or Gekko documentation

Implement

• [x] Merge the content of readme.md of openbot/core into this tool and list it as a "Documentation" tab on https://openbot.tech/#/

[seichris]

https://www.gitbook.com is pretty common

[Kisgus]

Done, ty @seichris

https://openbot.gitbook.io/project/