update syntax to allow for non-FQDN domains or IP addresses in ServerName.

Since UseCanonicalName defaults to OFF, name-based vhosts isn't really an
"additional" purpose of a ServerName. Also update the syntax to not insist
on an FQDN -- generally the ServerName needs to be something the client
and server can both resolve, but it's not required to be an FQDN or even
a domain name.

Leave the example as www.example.com



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1725102 13f79535-47bb-0310-9956-ffa450edef68