Mention notable things added in 2.4.x

Mention mod_macro, mod_wstunnel, mod_authnz_fcgi and a few other notable
features that were added post 2.4.0


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1661464 13f79535-47bb-0310-9956-ffa450edef68