Merge r1031428 from trunk:

PR#47348: missing "response" the ProxyBadHeader description, 
and drive home with  ...from the origin server.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1031429 13f79535-47bb-0310-9956-ffa450edef68