minor changes to tutorial
minor changes to tutorial

alubbock/pysb,neurord/pysb,alubbock/pysb-legacy,spgarbet/pysb,LoLab-VU/pysb,spgarbet/pysb,LoLab-VU/pysb,neurord/pysb,d-fan/pysb,jmuhlich/pysb,johnbachman/pysb,johnbachman/pysb,alubbock/pysb-legacy,pysb/pysb,alubbock/pysb-legacy,spgarbet/pysb,d-fan/pysb,d-fan/pysb,alubbock/pysb-legacy,neurord/pysb