Documentation

[benjaoming]

Description

At some point soon, the main README should be turned into documentation.

It would be great to use Daniele Procida's pattern: https://www.youtube.com/watch?v=t4vKPhjcMZg

[benjaoming]

Partly addressed in #19

Docs are now visible here: https://django-consent.readthedocs.io/en/latest/