deletes deleted example from README.md (#1438)

Author: benjaminbecker

examples/asyncio/websocket/echo/README.md

@@ -24,10 +24,6 @@ To run the Python client
 
     python client.py ws://127.0.0.1:9000
 
-or (Python 3)
+or
 
     python client_coroutines.py ws://127.0.0.1:9000
-
-or (Python 2)
-
-    python client_coroutines_py2.py ws://127.0.0.1:9000