Remove image from readme, and link demo to site (#521)

README.rst

@@ -6,7 +6,7 @@
 .. _wyrm: http://www.github.com/snide/wyrm/
 .. _grunt: http://www.gruntjs.com
 .. _node: http://www.nodejs.com
-.. _demo: http://docs.readthedocs.org
+.. _demo: https://sphinx-rtd-theme.readthedocs.io/en/latest/
 .. _hidden: http://sphinx-doc.org/markup/toctree.html
 
 .. image:: https://img.shields.io/pypi/v/sphinx_rtd_theme.svg
@@ -35,9 +35,6 @@ If you'd like to update the theme,
 please make your edits to the SASS files here,
 rather than the .css files on checked into the repo.
 
-.. image:: demo_docs/source/static/screen_mobile.png
-    :width: 100%
-
 Installation
 ============