Add CloseEvent external

src/client/websocket/WebSocketManager.js

@@ -229,6 +229,11 @@ class WebSocketManager extends EventEmitter {
     this.sequence = -1;
   }
 
+  /**
+   * @external CloseEvent
+   * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent}
+   */
+
   /**
    * Run whenever the connection to the gateway is closed, it will try to reconnect the client.
    * @param {CloseEvent} event The WebSocket close event