Add doc linting to pep8 target

This adds doc8 linting to validate our docs. Fixes minor issues with our
HACKING doc that this found.

Change-Id: I1d9277f11e2017fb15e6286d15c4cb70727ef12d
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

HACKING.rst

@@ -1,4 +1,4 @@
 brick-python-cinderclient-ext Style Commandments
-===============================================
+================================================
 
 Read the OpenStack Style Commandments https://docs.openstack.org/hacking/latest/

lower-constraints.txt

@@ -9,6 +9,7 @@ cmd2==0.8.1
 coverage==4.0
 ddt==1.0.1
 debtcollector==1.19.0
+doc8==0.6.0
 docutils==0.14
 dulwich==0.19.0
 enum-compat==0.0.2

test-requirements.txt

@@ -11,3 +11,4 @@ oslotest>=3.2.0 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
 stestr>=1.0.0 # Apache-2.0
+doc8>=0.6.0 # Apache-2.0

tox.ini

@@ -29,7 +29,9 @@ commands =
 whitelist_externals = find
 
 [testenv:pep8]
-commands = flake8 {posargs}
+commands =
+  flake8 {posargs}
+  doc8
 
 [testenv:fast8]
 envdir = {toxworkdir}/pep8
@@ -94,6 +96,10 @@ show-source = True
 builtins = _
 exclude=.venv,.git,.tox,dist,doc/*,*lib/python*,*egg,build
 
+[doc8]
+ignore-path=.tox,*.egg-info,doc/src/api,doc/source/drivers.rst,doc/build,.eggs/*/EGG-INFO/*.txt,doc/so    urce/configuration/tables,./*.txt,releasenotes/build
+extension=.txt,.rst,.inc
+
 [testenv:lower-constraints]
 deps =
   -c{toxinidir}/lower-constraints.txt