Remove one more stray reference to pep8
Remove one more stray reference to pep8

We switched to pycodestyle then flake8 recently, but one stray
reference to pep8 was left in this doc file.

Signed-off-by: Adam Williamson <9343557fe728326ecca60ea600eccabb6754179b@redhat.com>

mwclient/mwclient