Added a link to the Sphinx documentation about setuptools entry points

Author: segevfiner

setup.py

@@ -27,6 +27,7 @@
         'static/font/*.*'
     ]},
     include_package_data=True,
+    # See http://www.sphinx-doc.org/en/stable/theming.html#distribute-your-theme-as-a-python-package
     entry_points = {
         'sphinx.html_themes': [
             'sphinx_rtd_theme = sphinx_rtd_theme',