improve hello-world example on website

doc/index.html

@@ -65,12 +65,13 @@ Server running at http://127.0.0.1:8124/</pre>
 
       <pre>
 var net = require('net');
-net.createServer(function (socket) {
+
+var server = net.createServer(function (socket) {
   socket.write("Echo server\r\n");
-  socket.on("data", function (data) {
+  socket.pipe(socket);
-    socket.write(data);
+})
-  });
+
-}).listen(8124, "127.0.0.1");
+server.listen(8124, "127.0.0.1");
 </pre>
 
       <p>