clarifying Monophonic comment
clarifying Monophonic comment

Addresses #98

Tonejs/Tone.js,lukephills/Tone.js,BlokDust/Tone.js,lukephills/Tone.js,TONEnoTONE/Tone.js,TONEnoTONE/Tone.js,BlokDust/Tone.js,Tonejs/Tone.js