Sylvia/docs/sfd

@mhoeber @lamagnifica SFD_ORA.rst and SFD_mathformatting.rst are ready for a dev review when you guys have the time. (SFD_certificates is still in the writing phase, so ignore that one for now.) Thanks!
I'm not quite sure what the first sentence is trying to say. Scores aren't calculated "by criteria". Is the gist that by using the median, no single one of your peers determines your final score? 
thus --> as a result,