Updated purge additional fields example

Author: pweston

README.md

@@ -350,8 +350,8 @@ class User extends \LaravelBook\Ardent\Ardent {
 You can also purge additional fields. The attribute `Ardent::$purgeFilters` is an array of closures to which you can add your custom rules. Those closures receive the attribute key as argument and should return `false` for attributes that should be purged. Like this:
 
 ```php
-function __construct() {
-  parent::__construct();
+function __construct($attributes = array()) {
+  parent::__construct($attributes);
 
   $this->purgeFilters[] = function($key) {
     $purge = array('tempData', 'myAttribute');