[pre-commit] Add initial pre-commit config

This change adds configuration for the pre-commit tool,
follow-up changes will address the remaining issues in a phased
approach to make the reviews simpler.

This is based on the pre-commit config used in nova
with some additional hooks.

Follow-up changes will address the FIXME comments
related to sphinx-lint and codespell, as well as update tox
to enforce these checks in ci.

Change-Id: I87681a19f7fa88366c2b0d310c8b3153aa6a137b

doc/source/conf.py

@@ -115,7 +115,7 @@ html_theme = 'openstackdocs'
 htmlhelp_basename = '%sdoc' % project
 
 
-#openstackdocstheme options
+# openstackdocstheme options
 openstackdocs_repo_name = 'openstack/watcher'
 openstackdocs_pdf_link = True
 openstackdocs_auto_name = False