This patch set changes Drydock's exceptions documentation
(contained underneath operators guide) because it isn't rendering
correctly as a list table on RTD (the autoexception information
is missing) [0].
The easy fix is to change the tabularized view (list table)
into basically a series of autoexception classes which sufficiently
captures the level of detail required, anyway.
Note that running `tox -e docs` locally and opening the resulting
index.html page appears to work -- but not when hosted on RTD.
[0] https://airship-drydock.readthedocs.io/en/latest/exceptions/exceptions.html
Change-Id: Ie4bc01f1fe6aee9b9a58fd956f5b350df44bef51
3fb095f0eb