Add optional spell checker target

Add a tox target using sphinxcontrib-spelling to let
authors run a spell checker against documents before
submitting them.

Change-Id: If519fb63bc4b0923a48df9e0435125fd66ab5c0c

{{cookiecutter.repo_name}}/doc/source/conf.py

@@ -26,6 +26,14 @@ extensions = [
     'oslosphinx'
 ]
 
+# Optionally allow the use of sphinxcontrib.spelling to verify the
+# spelling of the documents.
+try:
+    import sphinxcontrib.spelling
+    extensions.append('sphinxcontrib.spelling')
+except ImportError:
+    pass
+
 # autodoc generation is a bit aggressive and a nuisance when doing heavy
 # text edit cycles.
 # execute "export SPHINX_DEBUG=1" in your terminal to disable

{{cookiecutter.repo_name}}/tox.ini

@@ -11,9 +11,15 @@ setenv =
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
-
 [testenv:venv]
 commands = {posargs}
 
 [testenv:docs]
 commands = python setup.py build_sphinx
+
+[testenv:spelling]
+deps =
+   -r{toxinidir}/requirements.txt
+   sphinxcontrib-spelling
+   PyEnchant
+commands = sphinx-build -b spelling doc/source doc/build/spelling