try to get rtd to see our master doc

etc/docs/conf.py

@@ -94,7 +94,7 @@ if not on_rtd:  # only import and set the theme if we're building docs locally
     html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
 
 if on_rtd:
-    master_doc = '../../docs/index.rst'
+    master_doc = '../../docs/index'
 
 # 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,