Merge r1661464:

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/branches/2.4.x@1661466 13f79535-47bb-0310-9956-ffa450edef68