added a clarification about separation of proxy functionality and mod_cache;

added a link to mod_ssl (for proxy directives)

submitted by Irmund Thum <i.t@ithum.de>

with two minor corrections from me


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97043 13f79535-47bb-0310-9956-ffa450edef68