Addition of delay effect to the kitchen

Please add this delay pedal to pedalboard.js repository. I think this is a nice addition to this library. I also updated your example for the demonstration of the pedalboard.js. I added a delay pedal in-between the overdrive and reverb effects, and I provided states for your 5 demonstration examples, where delay effect is applied on sample1, sample4 and sample5.
you should leave two empty lines between each method and property declaration.