Encourage people to look at ./configure --help

Several people this week have seemed to think that this document should
list all the options. Perhaps that's not entirely unreasonable, but it
isn't going to happen any time soon.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@527129 13f79535-47bb-0310-9956-ffa450edef68