[FrameworkBundle] Fix cookie_secure default value

Author: Mathieu

reference/configuration/framework.rst

@@ -1704,7 +1704,7 @@ The possible values for this option are:
 cookie_secure
 .............
 
-**type**: ``boolean`` or ``'auto'`` **default**: ``'auto'``
+**type**: ``boolean`` or ``'auto'`` **default**: ``false``
 
 This determines whether cookies should only be sent over secure connections. In
 addition to ``true`` and ``false``, there's a special ``'auto'`` value that