add canonical_url to Sphinx config

Author: stevepiercy

docs/conf.py

@@ -91,7 +91,10 @@
 # Add and use Pylons theme
 html_theme = 'pylons'
 html_theme_path = pylons_sphinx_themes.get_html_themes_path()
-html_theme_options = dict(github_url='http://github.com/Pylons/waitress')
+html_theme_options = dict(
+    github_url='http://github.com/Pylons/waitress',
+    canonical_url='http://docs.pylonsproject.org/projects/waitress/en/latest/'
+)
 
 # The style sheet to use for HTML and HTML Help pages. A file of that name
 # must exist either in Sphinx' static/ path, or in one of the custom paths