Merge r832759 from trunk:

ServerAlias and Listen accumulate, not supercede.  The latter of course is n/a to vhosts!

Additional rewording of vhost details.

PR48125



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@832902 13f79535-47bb-0310-9956-ffa450edef68