Improve documentation of ${SIPDOMAIN}

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@1731 65c4cc65-6c06-0410-ace0-fbb531ad65f3

README.variables

@@ -44,7 +44,7 @@ ${UNIQUEID}	Current call unique identifier
 ${DNID}         Dialed Number Identifier
 ${RDNIS}        Redirected Dial Number ID Service
 ${HANGUPCAUSE}	Hangup cause on last PRI hangup
-${SIPDOMAIN}    SIP domain (if appropriate)
+${SIPDOMAIN}    SIP destination domain of an inbound call (if appropriate)
 
 There are two reference modes - reference by value and reference by name. 
 To refer to a variable with its name (as an argument to a function that 

doc/README.variables

@@ -44,7 +44,7 @@ ${UNIQUEID}	Current call unique identifier
 ${DNID}         Dialed Number Identifier
 ${RDNIS}        Redirected Dial Number ID Service
 ${HANGUPCAUSE}	Hangup cause on last PRI hangup
-${SIPDOMAIN}    SIP domain (if appropriate)
+${SIPDOMAIN}    SIP destination domain of an inbound call (if appropriate)
 
 There are two reference modes - reference by value and reference by name. 
 To refer to a variable with its name (as an argument to a function that