Make documentation and error messages of APACI's --activate-module=FILE

option more clear.

Submitted by: Jan Wolter <janc@wwnet.net>
PR: 3995


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82888 13f79535-47bb-0310-9956-ffa450edef68