Document pattern for materializing most specific taxon constraints for a class

[cmungall]

Note: this is strictly outside the scope of the actual ontology itself, but one of the main uses for ncbitaxon in OBO is TCs, we need a central place to document these (could also move this to RO tracker?)

We should make it easy to materialize the most specific non-redundant TCs on a per-class basis

Note quite possible in robot yet:
ontodev/robot#1213

@balhoff and @kltm have experimented with doing this in GO