Update README.md

Fix url to the example demo. Please, only pull after accepting this PR: https://github.com/wix/react-native/pull/2

README.md

 ### Real world examples
 
 <img src="https://github.com/wix/react-native/blob/master/src/videos/demo.gif?raw=true" width="240">&nbsp;&nbsp;&nbsp;&nbsp;
-<img src="https://image.ibb.co/kTbvX5/rnn_example_demo.gif" width="240">
+<img src="https://github.com/wix/react-native/blob/master/src/videos/rnn-example-demo.gif?raw=true" width="240">
 
 On the left - The Wix app.