added comment

regarding set point initial state forcing

I_Mihalache_AudioPlayer.ino

@@ -348,7 +348,7 @@ void setup() {
   setPoint.begin(threshold, hysteresis);
   setPoint.attach(RISING_EDGE, Presence);
   setPoint.attach(FALLING_EDGE, Absence);
-  setPoint.update(0);
+  setPoint.update(0); // force no presence state at startup
 }
 
 ///////////////////////////////////////////////////////////////////