Add some more information about the SIP Disclaimer header.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@66856 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/sip.conf.sample

@@ -488,6 +488,8 @@ srvlookup=yes			; Enable DNS SRV lookups on outbound calls
 ;                       ; "Please reply to sender that you have received the message in error, " 
 ;                       ; "then delete it. Thank you."
 ;
+; NOTE: THIS IS A JOKE.  IT IS ACCEPTABLE TO LAUGH.
+;
 ;-----------------------------------------------------------------------------------
 
 [authentication]