added small comment about <hostname>

svn path=/icecast/trunk/icecast/; revision=6603

conf/icecast.xml.in

@@ -32,6 +32,9 @@
     </directory>
      -->
 
+    <!-- This is the hostname other people will use to connect to your server.
+    It affects mainly the urls generated by Icecast for playlists and yp
+    listings. -->
     <hostname>localhost</hostname>
 
     <!-- You can use these two if you only want a single listener -->