Add check for rst syntax

Creating the release would fail if the syntax of README.rst is not
correct. Let's check it in the pep8 environment.

Story: 2002163
Task: 23044
Change-Id: I2856622af08cec7c801959ca85f4c77252263db5

lower-constraints.txt

@@ -3,6 +3,7 @@ Babel==2.3.4
 bandit==1.4.0
 coverage==4.0
 debtcollector==1.2.0
+docutils==0.11
 extras==1.0.0
 fixtures==3.0.0
 flake8==2.5.5

test-requirements.txt

@@ -16,3 +16,4 @@ requests-mock>=1.2.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
+docutils>=0.11

tox.ini

@@ -68,6 +68,7 @@ basepython = python3
 commands =
   {[testenv:flake8]commands}
   {[testenv:bandit]commands}
+  python setup.py check --restructuredtext --strict
 
 [testenv:venv]
 basepython = python3