Document addition of variable from Touch Monitor.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@7408 65c4cc65-6c06-0410-ace0-fbb531ad65f3

doc/README.variables

@@ -647,6 +647,7 @@ ${RECORDED_FILE} 	* Recorded file in record()
 ${TALK_DETECTED} 	* Result from talkdetect()
 ${TOUCH_MONITOR} 	The filename base to use with Touch Monitor (auto record)
 ${TOUCH_MONITOR_FORMAT} The audio format to use with Touch Monitor (auto record)
+${TOUCH_MONITOR_OUTPUT} * Recorded file from Touch Monitor (auto record)
 ${TXTCIDNAME}		* Result of application TXTCIDName
 ${VPB_GETDTMF}		chan_vpb