Update README.md

Author: abdelouahabb

examples/Tornado-example/README.md

@@ -17,7 +17,7 @@ node server.js
 Start the python server
 
 ```
-python tornado-ex.py
+python app.py
 ```
 
 And visit [http://127.0.0.1:8000](http://127.0.0.1:8000)