swapped comment and opening in xml configuration example

Author: Maxime Douailin

cookbook/security/pre_authenticated.rst

@@ -34,8 +34,8 @@ Enable the x509 authentication for a particular firewall in the security configu
 
     .. code-block:: xml
 
-        <?xml version="1.0" ?>
         <!-- app/config/security.xml -->
+        <?xml version="1.0" ?>
         <srv:container xmlns="http://symfony.com/schema/dic/security"
             xmlns:srv="http://symfony.com/schema/dic/services">
 
@@ -107,8 +107,8 @@ corresponding firewall in your security configuration:
 
     .. code-block:: xml
 
-        <?xml version="1.0" ?>
         <!-- app/config/security.xml -->
+        <?xml version="1.0" ?>
         <srv:container xmlns="http://symfony.com/schema/dic/security"
             xmlns:srv="http://symfony.com/schema/dic/services">