add "exclude-from-classmap" description to 04-schema.md
add "exclude-from-classmap" description to 04-schema.md

hirak/composer,remicollet/composer,phansys/composer,nevvermind/composer,SpacePossum/composer,Danack/composer,alcohol/composer,bd808/composer,stof/composer,MoT3rror/composer,Seldaek/composer,curry684/composer,JBleijenberg/composer,milleruk/composer,nicolas-grekas/composer,staabm/composer,yaman-jain/composer,balbuf/composer,erasys/composer,composer/composer,fabiang/composer,Teino1978-Corp/Teino1978-Corp-composer,DiceHoldingsInc/composer,davidolrik/composer,floverdevel/composer,johnstevenson/composer,Soullivaneuh/composer,jreinke/composer,slbmeh/composer,stefangr/composer,till/composer,localheinz/composer,fabpot/composer,pierredup/composer,dzuelke/composer,andrerom/composer,javihgil/composer,vdm-io/composer,naderman/composer,gencer/composer