update readme

internal/websocket/server.go

@@ -149,6 +149,6 @@ func (s *Server) HandleMessage(ws *websocket.Conn, msg []byte) {
 
 func (s *Server) SendPong(ws *websocket.Conn) {
 	if err := ws.WriteMessage(websocket.PongMessage, nil); err != nil {
-		log.Printf("error sending pong", err)
+		log.Printf("error sending pong: %v", err)
 	}
 }