Fix typo in README.md example

README.md

@@ -11,7 +11,7 @@ use tungstenite::server::accept;
 let server = TcpListener::bind("127.0.0.1:9001").unwrap();
 for stream in server.incoming() {
     spawn (move || {
-        let mut websocket = accept(stream.unwrap(), None).unwrap();
+        let mut websocket = accept(stream.unwrap()).unwrap();
         loop {
             let msg = websocket.read_message().unwrap();