add link to the changelog

Author: ocefpaf

README.rst

@@ -69,3 +69,10 @@ See `our complete contributor's guide <https://github.com/python-visualization/f
 
 
 .. |folium| image:: http://python-visualization.github.io/folium/docs-master/_images/folium_logo.jpg
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+
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+Contributing
+------------
+
+Check the `changelog <https://raw.githubusercontent.com/python-visualization/folium/master/CHANGES.txt>`_ for a detailed list of the latest changes.