[sfFormExtraPlugin] added some information in the README file (closes #6630)
[sfFormExtraPlugin] added some information in the README file (closes #6630)

git-svn-id: f41589186f8abcf1a02f376b76259e41ac2d2802@24545 ee427ae8-e902-0410-961c-c3ed070cd9f9

aalbagarcia/sfFormExtraPlugin_1.3,aalbagarcia/sfFormExtraPlugin_1.3