update

Author: xingsy97

sdk/webpubsub-socketio-extension/examples/admin-ui/README.md

@@ -23,8 +23,9 @@ Besides, it contains server-side logic for a simple echo performance benchmark.
 
 ## Note
 - Azure Socket.IO Admin UI only supports single server application now.
-The line below is necessary to make the Admin UI work
+The two lines below are necessary to make the Admin UI work
     ```javascript
+    const { Namespace } = require("socket.io");
     Namespace.prototype["fetchSockets"] = async function() { return this.local.fetchSockets(); };
     ```