Improve documentation for generateSkirtBrim
Improve documentation for generateSkirtBrim

Contributes to issue CURA-1678.

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