Use digitalWrite for buzzer instead of Piezo object

[Michele Ferri]

It's meaningless to use the Piezo lib for an active buzzer that can only output 1 note. Use this

board.on("ready", function() {

    this.pinMode(3, five.Pin.OUTPUT);
    this.digitalWrite(3, 1);
    this.wait(1500, function() {
        board.digitalWrite(3, 0);
    });
});