Merge r1354427 from https://svn.apache.org/repos/asf/httpd/httpd/trunk/:

re-emphasize this paragraph in ProxyRequests is for fwd proxy



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1354430 13f79535-47bb-0310-9956-ffa450edef68