Clarify that the currently implemented material effects in GSF are electron related
After a discussion with @amorley clarify that the currently implemented material effects in GSF are electron related.
In theory one could implement other effects following the IMaterialMixtureConvolution
interface if interest arises.
Also, consolidate the old style configs a bit (we have done this already for the C.A ones)
Edited by Christos Anastopoulos