Add doc/requirements.txt file with doc requirements
The sphinx jobs need to find doc requirements in either
test-requiremnts.txt or doc/requirements.txt. Putting them directly in
to tox.ini, not so much.
Change-Id: I98a43b511a6949fa4f00c26eec224d24d6fa6588
diff --git a/doc/requirements.txt b/doc/requirements.txt
new file mode 100644
index 0000000..e140bc0
--- /dev/null
+++ b/doc/requirements.txt
@@ -0,0 +1,10 @@
+pbr>=2.0.0,!=2.1.0
+
+Pygments
+docutils
+sphinx>=1.6.2
+openstackdocstheme>=1.11.0
+nwdiag
+blockdiag
+sphinxcontrib-blockdiag
+sphinxcontrib-nwdiag