Fix grammar mistake
Fix grammar mistake

Suggested by Jorg.

totalretribution/Cura,senttech/Cura,ynotstartups/Wanhao,Curahelper/Cura,Curahelper/Cura,hmflash/Cura,totalretribution/Cura,fieldOfView/Cura,senttech/Cura,ynotstartups/Wanhao,hmflash/Cura,fieldOfView/Cura