Correct useAttributeAsKey usage

Author: danrot

components/config/definition.rst

@@ -327,8 +327,8 @@ In order to maintain the array keys use the ``useAttributeAsKey()`` method::
         ->fixXmlConfig('connection')
         ->children()
             ->arrayNode('connections')
+                ->useAttributeAsKey('name')
                 ->prototype('array')
-                    ->useAttributeAsKey('name')
                     ->children()
                         ->scalarNode('table')->end()
                         ->scalarNode('user')->end()