Switch to newer openstackdocstheme version

Switch to openstackdocstheme 2.2.1 version. Using
this version will allow especially:
* Linking from HTML to PDF document
* Allow parallel building of documents
* Fix some rendering problems

Update Sphinx version as well.

Change pygments_style to 'native' since old theme version always used
'native' and the theme now respects the setting and using 'sphinx' can
lead to some strange rendering.

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

See also
http://lists.openstack.org/pipermail/openstack-discuss/2020-May/014971.html

Change-Id: Id95a6d2403c03cb909a37820f07d28107c5b02b2

doc/source/conf.py

@@ -65,9 +65,9 @@ title = 'OpenStack-Ansible ' + role_name + ' Documentation'
 
 
 # openstackdocstheme options
-repository_name = 'openstack/' + target_name
-bug_project = project.lower()
-bug_tag = ''
+openstackdocs_repo_name = 'openstack/' + target_name
+openstackdocs_bug_project = project.lower()
+openstackdocs_bug_tag = ''
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
@@ -102,7 +102,7 @@ exclude_patterns = []
 # show_authors = False
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = 'native'
 
 # A list of ignored prefixes for module index sorting.
 # modindex_common_prefix = []

requirements.txt

@@ -3,6 +3,6 @@
 # process, which may cause wedges in the gate later.
 
 # this is required for the docs build jobs
-sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
-openstackdocstheme>=1.32.1 # Apache-2.0
+sphinx>=2.0.0,!=2.1.0 # BSD
+openstackdocstheme>=2.2.1 # Apache-2.0
 doc8>=0.6.0 # Apache-2.0