Don't enumerate event types in section 3.4

When adding an event type we expect spec authors to edit both section 3.4 and
4.1.x. This is error prone...

  https://trac.torproject.org/10085

Dropping the redundant listing of event types and simply citing 4.1.x.
Describing CONN_BW's ConnType

Our new CONN_BW events' ConnType enumeration is poorly defined...

  https://trac.torproject.org/10086

This is just a guess on my part for what it's supposed to be. I have *not*
trudged through the tor code to puzzle out how it actually allocates this
enumeration.
Merge remote-tracking branches 'atagar/10086' and 'atagar/10085'