Fix line direction mix-up in documentation
Fix line direction mix-up in documentation

The point is before ab, or after ba.

Contributes to issue CURA-2296.

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