Rule statement clarity

A tiny adjustment to rules surrounding discoveries.

The analysis stations intent was that the first instance of +d allows an analysis check to be performed, and every additional +d is a bonus, this was not super clear, I added the word "extra" to  try and impose this restriction of effect.

Similarly I added a "+" to the "d" in the section about post combat analysis bonus checks, clarifying that it is the modifier  of the encounter, not just any old random 'd' laying about...