Add doc for outline comparison to support.h
Add doc for outline comparison to support.h

CURA-2724

ROBO3D/CuraEngine,ROBO3D/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,alephobjects/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,ROBO3D/CuraEngine