More Modules

Taking advantage of some free time during the holiday, I've ported over the docs for another pair of modules that I built and installed a while ago: Random Noise and the '398 SNH.

These are both mostly direct implementations of existing designs. The noise source is based on the MFOS Noise Cornucopia and the sample and hold is based on Rene Schmitz's YASH. Both came togther without a fuss, but I did spend some time on filter design for both - details are on the project pages.