Added info about debugFastRefresh in system_settings.js

Author: dribnet

system_settings.js

@@ -1,4 +1,6 @@
 // smoothing is applied to the audio file to smooth the signal
 // expected values are from 0 (no smoothing) to 100 (lots of smoothing)
 const smoothing = 25;
+
+// debugFastRefresh can be set to true to go straight to the song
 const debugFastRefresh = false;