Provide brief definition of scoring/ranking algorithm

[karafecho]

This issue is to strongly recommend that we provide a brief definition of the ROBOKOP scoring/ranking algorithm to users by way of hovering over the "score" column in answer sets or perhaps providing a legend somewhere on the question-builder.

Here's a draft definition (sans references):

The ROBOKOP scoring/ranking algorithm employs formalism developed within electrical resistance theory. In brief, the algorithm finds the highest scoring path between a pair of nodes of interest, and the scores are based primarily on publication support for edges. These edges are either derived from curated knowledge sources and/or contributed by a ROBOKOP service termed OmniCorp, which exposes entity co-occurrence terms derived from PubMed abstracts; the former are weighted more heavily than the latter. The scores that are assigned to specific answer subgraphs within a result set should be considered relative to one another and not absolute or comparable across result sets.