docs: show cloudbase-init version

Previously, the docs version was hardcoded to 1.0,
which was incorrect.

Now the version and release field will show the
actual cloudbase-init package version.

Example: 0.9.11 or 0.9.12
Change-Id: Ide4ed289029e25c39c07fec53086ff8868ce4063

doc/source/conf.py

@@ -16,6 +16,8 @@ import sys
 import os
 import shlex
 
+from cloudbaseinit import version as cbs_version
+
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
@@ -60,9 +62,10 @@ author = u'Cloudbase Solutions Srl'
 # built documents.
 #
 # The short X.Y version.
-version = '1.0'
+version = cbs_version.get_canonical_version()
+
 # The full version, including alpha/beta/rc tags.
-release = '1.0'
+release = version
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.