More annotations for the FluidSlicers' `metric`

[tedmoore]

During our NOTAM workshop one of the participants suggested that we annotate the metric options with more useful descriptions similar to how SuperCollider's Onsets object is described (see below). It says which settings might be good for which types of sounds. We can also provide some guidance on "Where to start" / "Which one to start with" and why one might try other metric options.

Does a general annotation of this already exist in one of our brains?

I think this should exist in the CCEs which is easy to add to this repo and I also think it should exist on the web materials.