Add docs build options and theme requirements (#818)

diff --git a/docs/conf.py b/docs/conf.py
index 70960de..881c068 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -44,7 +44,7 @@
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'alabaster'
+html_theme = 'python_docs_theme'
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,