Renamed once method to pull to match the latest update.

Author: Garbee

session.md

@@ -35,7 +35,7 @@ The session configuration is stored in `app/config/session.php`. Be sure to revi
 	$value = Session::get('key', function() { return 'default'; });
 
 #### Retrieving An Item and Forgetting It
-	$value = Session::once('key', 'default');
+	$value = Session::pull('key', 'default');
 
 #### Retrieving All Data From The Session