Update README.md

README.md

 - functions to add:
 - 
-- player volume control
 - player directory listing
 - 'setsymboliclink & play'
 
@@ -9,6 +8,8 @@
 -
 -- command/hidegui -m 0/1  to show or hide the gui  
 -- command/status -m dum   will publish 1 or 0 to stat/prefix  
+-- command/volume -m 50    will set the volume to 50%
+
 
 MQTT addon for Kodi
 ===================