Merge pull request #649 from bjfletcher/master

Added a note about the library being available on the CDN

Author: mjackson

README.md

@@ -41,6 +41,8 @@ installed from npm.
 There is also a global build available on bower, find the library on
 `window.ReactRouter`.
 
+The library is also available on the popular CDN [cdnjs](https://cdnjs.com/libraries/react-router).
+
 Features
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