Fix typo in English translation
Fix typo in English translation

Can't fix the actual typo in code due to the string freeze though.

Contributes to issue CURA-570.

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