Treat doc warnings as errors

This adds a flag to the sphinx-build command to treat warnings
as errors.

It also cleans out the old doc related entries from setup.cfg
since docs are no longer built using that method.

Change-Id: I1bacf231605ab791d4b817223ab64be2a4133672

setup.cfg

@@ -27,14 +27,5 @@ console_scripts =
     oslo-rootwrap = oslo_rootwrap.cmd:main
     oslo-rootwrap-daemon = oslo_rootwrap.cmd:daemon
 
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-warning-is-error = 1
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
 [wheel]
 universal = 1

tox.ini

@@ -35,7 +35,7 @@ commands = {posargs}
 
 [testenv:docs]
 deps = -r{toxinidir}/doc/requirements.txt
-commands = sphinx-build -b html doc/source doc/build/html
+commands = sphinx-build -W -b html doc/source doc/build/html
 
 [flake8]
 show-source = True