Update app.js

fixed example route syntax

Author: jamdon

app.js

@@ -1,4 +1,4 @@
 //  in this file create an express application - use the middle-ware built into express
 //  to serve up static files from the public directory (index.html and client.js - you 
 //  can also serve up css files from the public directory this way if you want)
-//  you need to support a '/trucks' endpoint, and a dynamic route for '/trucks:name'
+//  you need to support a '/trucks' endpoint, and a dynamic route for '/trucks/:name'