message: update sampler example
  Fixes
  [skip ci]
diff: @@ -11,7 +11,7 @@ function(Tone){
  * @param {String} url the url of the audio file
  * @param {Function=} onload The callback to invoke when the sample is loaded.
  * @example
  - * var sampler = new Sampler("./audio/casio/A1.mp3", function(){
  + * var sampler = new Tone.Sampler("./audio/casio/A1.mp3", function(){
  * //repitch the sample down a half step
  * sampler.triggerAttack(-1);
  * }).toMaster();
  