Applies patch provided by Luke Meyer in...

Applies patch provided by Luke Meyer in https://issues.apache.org/bugzilla/show_bug.cgi?id=51131 - Adds usage example to mod_proxy_ajp docs.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1199557 13f79535-47bb-0310-9956-ffa450edef68