[docs] [issue28088] Document Transport.set_protocol and get_protocol

[Berker Peksag]

Changes by Berker Peksag <berker.peksag at gmail.com>:


----------
nosy:  -larry
priority: release blocker -> normal

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue28088>
_______________________________________