Switch to newer openstackdocstheme version

Switch to openstackdocstheme 2.2.1 version and use it
instead of retired oslosphinx. 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

Add .zuul.yaml with specs-jobs template so that this repo has jobs.

Change-Id: I8e9ad94f6e0586fbb50512515f3a33136c4502b1

.zuul.yaml

@@ -0,0 +1,3 @@
+- project:
+    templates:
+      - openstack-specs-jobs

doc/source/conf.py

@@ -23,12 +23,12 @@ sys.path.insert(0, os.path.abspath('../..'))
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = [
     'sphinx.ext.autodoc',
-    'oslosphinx',
+    'openstackdocstheme',
     'yasfb',
 ]
 
 # Feed configuration for yasfb
-feed_base_url = 'http://specs.openstack.org/openstack/swift-specs'
+feed_base_url = 'https://specs.openstack.org/openstack/swift-specs'
 feed_author = 'OpenStack Swift Team'
 
 exclude_patterns = [
@@ -58,6 +58,9 @@ master_doc = 'index'
 project = u'swift-specs'
 copyright = u'%s, OpenStack Foundation' % datetime.date.today().year
 
+# -- Options for openstackdocstheme -------------------------------------------
+openstackdocs_repo_name = 'openstack/swift-specs'
+
 # If true, '()' will be appended to :func: etc. cross-reference text.
 add_function_parentheses = True
 
@@ -66,7 +69,7 @@ add_function_parentheses = True
 add_module_names = True
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = 'native'
 
 # -- Options for HTML output --------------------------------------------------
 

requirements.txt

@@ -1,3 +1,3 @@
-oslosphinx
-sphinx>=1.1.2,<1.2
+openstackdocstheme>=2.2.1 # Apache-2.0
+sphinx>=2.0.0,!=2.1.0 # BSD
 yasfb>=0.5.1