Suggestion: add use case queries on wiki pages

[matentzn]

To properly judge the representational adequacy of a particular module of the model, and the model of the whole, it would be good to know what use case is driving. I suggest the following:

1. Every module page gets a human-readable description of the use case attached to it. That can be a couple of sentences describing the use case(s) that it is addressing. In a perfect world, maybe next year, this could be explicitly linked to an EJP use case description.
2. The use case is operationalised as a SPARQL query. This will make judging non-obvious questions easier: should something be modelled as a class or an individual? Etc etc.