Merge r578949 from trunk:

Clarify what happens if you don't have a ServerName in your
<VirtualHost>, since people sometimes assume that this
implies the host has no name, resulting in confusion.

Suggested by: Michael Rasmussen <mikeraz patch.com>



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@578951 13f79535-47bb-0310-9956-ffa450edef68