Add doc8 for documentation style checking, fix the one issue found

doc/source/usage.rst

@@ -369,7 +369,7 @@ To deploy the overcloud services in containers::
     (kayobe-venv) $ kayobe overcloud service deploy
 
 Once this command has completed the overcloud nodes should have OpenStack
-services running in Docker containers. 
+services running in Docker containers.
 
 Interacting with the Control Plane
 ----------------------------------

test-requirements.txt

@@ -5,5 +5,6 @@
 hacking>=0.12.0,<0.13 # Apache-2.0
 
 coverage>=4.0 # Apache-2.0
+doc8 # Apache-2.0
 sphinx>=1.5.1 # BSD
 oslotest>=1.10.0 # Apache-2.0

tox.ini

@@ -14,7 +14,10 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = unit2 discover {posargs}
 
 [testenv:pep8]
-commands = flake8 {posargs}
+commands =
+  flake8 {posargs}
+  # Check the *.rst files
+  doc8 README.rst CONTRIBUTING.rst doc/source --ignore D001
 
 [testenv:venv]
 commands = {posargs}