Added citation to contributing docs

docs/topics/contributing.md

 # Contributing to REST framework
 
+> The world can only really be changed one piece at a time. The art is picking that piece.
+>
+> — [Tim Berners-Lee][cite]
+
+## Running the tests
+
+## Building the docs
+
 ## Managing compatibility issues
 
 **Describe compat module**
 
-## Running the tests
-
+[cite]: http://www.w3.org/People/Berners-Lee/FAQ.html
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