Add CreateJS Sound.muted to Aud docs

Requests
1

Add CreateJS Sound.muted to Aud docs

Or consider a ZIM way of doing this... like F.muted

toggle.center(orthoControls).change(()=>{
createjs.Sound.muted = !toggle.toggled;
// if (backingSound) backingSound.fade(toggle.toggled?.02:0);
});