Switch to newer openstackdocstheme and reno versions

Switch to openstackdocstheme 2.2.0 and reno 3.1.0 versions. Using
these versions will allow especially:
* Linking from HTML to PDF document
* parallelizing building of documents

Update Sphinx version as well.

openstackdocstheme renames some variables, so follow the renames. A
couple of variables are also not needed anymore, remove them.

Set openstackdocs_pdf_link to link to PDF file.

Remove docs requirements from lower-constraints, they are not installed.

For more info. please refer [1].
[1] https://review.opendev.org/728938

Change-Id: I90d064e63baa5f067f38a881eb9a556dfb435e97

doc/requirements.txt

@@ -5,9 +5,9 @@
 # changes how packages are installed.  New dependencies should be
 # added in alphabetical order, however, some dependencies may need to
 # be installed in a specific order.
-openstackdocstheme>=1.20.0 # Apache-2.0
-reno>=2.5.0 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2 # BSD
+openstackdocstheme>=2.2.0 # Apache-2.0
+reno>=3.1.0 # Apache-2.0
+sphinx>=2.0.0,!=2.1.0 # BSD
 doc8>=0.6.0 # Apache-2.0
 
 # The below is rewquired to build testing module reference

doc/source/conf.py

@@ -72,9 +72,10 @@ extensions = [
 ]
 
 # openstackdocstheme options
-repository_name = 'openstack/horizon'
-bug_project = 'horizon'
-bug_tag = 'documentation'
+openstackdocs_repo__name = 'openstack/horizon'
+openstackdocs_repo_bug_project = 'horizon'
+openstackdocs_bug_tag = 'documentation'
+openstackdocs_pdf_link = True
 
 # Set aliases for extlinks
 # - generic launchpad bug - [:bug:`12345`]

lower-constraints.txt

@@ -50,7 +50,6 @@ munch==2.1.0
 netaddr==0.7.18
 netifaces==0.10.4
 nodeenv==0.9.4
-openstackdocstheme==1.20.0
 openstacksdk==0.11.2
 os-client-config==1.28.0
 os-service-types==1.2.0
@@ -101,7 +100,7 @@ python-swiftclient==3.2.0
 pytz==2013.6
 PyYAML==3.12
 rcssmin==1.0.6
-reno==2.5.0
+reno==3.1.0
 repoze.lru==0.7
 requests==2.14.2
 requestsexceptions==1.2.0
@@ -114,8 +113,6 @@ semantic-version==2.3.1
 simplejson==3.5.1
 six==1.10.0
 snowballstemmer==1.2.1
-Sphinx==1.6.5
-sphinxcontrib-websupport==1.0.1
 statsd==3.2.1
 stevedore==1.20.0
 tenacity==3.2.1

releasenotes/source/conf.py

@@ -44,9 +44,9 @@ extensions = [
 ]
 
 # openstackdocstheme options
-repository_name = 'openstack/horizon'
-bug_project = 'horizon'
-bug_tag = 'documentation'
+openstackdocs_repo_name = 'openstack/horizon'
+openstackdocs_bug_project = 'horizon'
+openstackdocs_bug_tag = 'documentation'
 
 # Set aliases for extlinks
 # - generic launchpad bug - [:bug:`12345`]