Clarify sound volume file usage in .ini

video_looper.ini

@@ -83,8 +83,11 @@ sound = both
 #sound = local
 
 # Sound volume output for the video player will be read from  a  file  near  the
-# video files. If the file does not exist, a default volume of 0db will be  used
-
+# video files. If the file does not exist, a default volume of 0db will be used.
+# To use this feature create a file in the same directory as the videos and name
+# it the value defined below (like 'sound_volume' by default), then inside the
+# file add a single line with the volume value in text to pass to omxplayer (using
+# its --vol option which takes a value in millibels).
 sound_vol_file = sound_volume
 
 # Any extra command line arguments to pass to omxplayer.  It is not recommended