Add CODING_STYLE document

This file is also borrowed from autotest, and already
reflects the updates to the coding style of the projects
under the autotest umbrella.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
More docstring fixes

Fix some extra problems with docstrings in the code tree.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>