Buzzer typo in Otto.init and buzzer init block missing

[dwijtsma]

The first block declares the buzzer with a capital 'Buzzer' and the buzzer block uses all lower case 'buzzer'.
The #define is just to make it work anyhow.

Next to this typo I think it would be good to have a buzzer init block, just like all other sound options. All buzzer blocks should come without a pin selection.