doc: fix net.createConnection() example

PR-URL: https://github.com/nodejs/node/pull/5219
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/net.markdown

@@ -578,7 +578,7 @@ Here is an example of a client of the previously described echo server:
 
 ```js
 const net = require('net');
-const client = net.connect({port: 8124}, () => {
+const client = net.createConnection({port: 8124}, () => {
   //'connect' listener
   console.log('connected to server!');
   client.write('world!\r\n');