Fix typo in Upgrade example.

doc.go

@@ -11,14 +11,14 @@
 // Conn:
 //
 //  func handler(w http.ResponseWriter, r *http.Request) {
-//      conn, err := websocket.Upgrade(w, r.Header, nil, 1024, 1024)
-//      if _, ok := err.(websocket.HandshakeError); ok {
-//          http.Error(w, "Not a websocket handshake", 400)
-//          return
-//      } else if err != nil {
-//          log.Println(err)
-//          return
-//      }
+//	    ws, err := websocket.Upgrade(w, r, nil, 1024, 1024)
+//	    if _, ok := err.(websocket.HandshakeError); ok {
+//		    http.Error(w, "Not a websocket handshake", 400)
+//		    return
+//	    } else if err != nil {
+//		    log.Println(err)
+//		    return
+//	    }
 //      ... Use conn to send and receive messages.
 //  }
 //