message: Fix typo in MembraneSynth description
  "applied during during ..." => "applied during ..."
diff: @@ -9,9 +9,9 @@ function(Tone){
  * with an amplitude envelope and frequency ramp. A Tone.OmniOscillator
  * is routed through a Tone.AmplitudeEnvelope to the output. The drum
  * quality of the sound comes from the frequency envelope applied
  - * during during Tone.MembraneSynth.triggerAttack(note). The frequency
  - * envelope starts at <code>note * .octaves</code> and ramps to
  - * <code>note</code> over the duration of <code>.pitchDecay</code>.
  + * during Tone.MembraneSynth.triggerAttack(note). The frequency envelope
  + * starts at <code>note * .octaves</code> and ramps to <code>note</code>
  + * over the duration of <code>.pitchDecay</code>.
  *
  * @constructor
  * @extends {Tone.Instrument}
  