This is intended to make docstrings shorter and to the point, as they should not start with "This module contains [..]" or "This class represents [..]".
It is unchecked by default as it is not part of the PEP257 standard.
Added D404: First word of a docstring should not be `This`
Merge from master
This pull request looks fine to me. The fact that it's off by default is helpful too.
Updated documentation, included D404 in our self-test.