Correct description of notifyringing option.

(Closes issue #12890)
Reported by gminet


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@123883 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/sip.conf.sample

@@ -197,7 +197,8 @@ srvlookup=yes			; Enable DNS SRV lookups on outbound calls
 ;subscribecontext = default	; Set a specific context for SUBSCRIBE requests
 				; Useful to limit subscriptions to local extensions
 				; Settable per peer/user also
-;notifyringing = yes		; Notify subscriptions on RINGING state (default: no)
+;notifyringing = yes           ; Control whether subscriptions already INUSE get sent
+                               ; RINGING when another call is sent (default: no)
 ;notifyhold = yes		; Notify subscriptions on HOLD state (default: no)
 				; Turning on notifyringing and notifyhold will add a lot
 				; more database transactions if you are using realtime.