Doc: 'wait' releases driver connection, not 'stop'

This change documents that MessageHandlingServer.wait
the released driver resources associated to this
MessageHandlingServer instance.

Like closing network connections to the broker.

Closes bug: #1397459

Change-Id: I3b0710faeb32ca8e9ee09b14aa1f79290c6061f5
Merge "Doc: 'wait' releases driver connection, not 'stop'"