Document the usefulness of explicit udp:// in the register string

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@238313 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/sip.conf.sample

@@ -617,6 +617,12 @@ srvlookup=yes                   ; Enable DNS SRV lookups on outbound calls
 ;
 ;    Note that in this example, the optional authuser and secret portions have
 ;    been left blank because we have specified a port in the user section
+;
+;register => tls://username:xxxxxx@sip-tls-proxy.example.org
+;
+;    The 'transport' part defaults to 'udp' but may also be 'tcp' or 'tls'.
+;    Using 'udp://' explicitly is also useful in case the username part
+;    contains a '/' ('user/name').
 
 ;registertimeout=20             ; retry registration calls every 20 seconds (default)
 ;registerattempts=10            ; Number of registration attempts before we give up