Fix docs sphinx requirements

Change-Id: Ib6009e622115ce007540f646178e171f25942099

doc/requirements.txt

@@ -1,8 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7'  # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4'  # BSD
+sphinx>=2.0.0,!=2.1.0 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
 openstackdocstheme>=1.18.1 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0

lower-constraints.txt

@@ -39,7 +39,6 @@ reno==2.5.0
 requests==2.14.2
 six==1.11.0
 SQLAlchemy==1.2.0
-sphinx==1.6.5
 stestr==1.0.0
 stevedore==1.20.0
 tenacity==5.0.2

releasenotes/source/conf.py

@@ -38,8 +38,16 @@
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
-    'oslosphinx',
-    'reno.sphinxext',
+    'sphinx.ext.autodoc',
+    'sphinx.ext.coverage',
+    'sphinx.ext.ifconfig',
+    'sphinx.ext.graphviz',
+    'sphinx.ext.todo',
+    'openstackdocstheme',
+    'oslo_config.sphinxext',
+    'oslo_config.sphinxconfiggen',
+    'oslo_policy.sphinxext',
+    'oslo_policy.sphinxpolicygen',
 ]
 
 # Add any paths that contain templates here, relative to this directory.