some explanations

Observer/User.php

@@ -5,7 +5,7 @@ namespace DesignPatterns\Observer;
 /**
  * Observer pattern : The observed object (the subject)
  * 
- * The subject maintains a list of Observer and send notificiations.
+ * The subject maintains a list of Observers and sends notifications.
  *
  */
 class User implements \SplSubject

Observer/UserObserver.php

@@ -18,6 +18,12 @@ namespace DesignPatterns\Observer;
 class UserObserver implements \SplObserver
 {
 
+    /**
+     * This is the only method to implement as an observer.
+     * It is called by the Subject (usually by SplSubject::notify() )
+     * 
+     * @param \SplSubject $subject
+     */
     public function update(\SplSubject $subject)
     {
         echo get_class($subject) . ' has been updated';