Document the specifics of how each connector interacts with events

[Cadair]

While we have tried to make the events framework generic and cross-connector there will be differences in interpretation and implementation of different events between connectors. (For example UserRole or Reply). We therefore should have an easy way for connector authors to document this, and also a nice concise way for users to see what events each connector supports and how they interpret them.

What I propose is that we integrate the documentation of how connectors support events into the @register_event decorator. This decorator could capture all of the docstrings for the decorated method and then output a reformatted list of supported events with their docstrings somewhere as part of the sphinx build

[jacobtomlinson]

That would be awesome!