update en-GB translation
update en-GB translation

Change-Id: Ibf97e16deb9886a11af69473f4244dddc5a592ef

grahamb/canvas-lms,grahamb/canvas-lms,SwinburneOnline/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,venturehive/canvas-lms,djbender/canvas-lms,SwinburneOnline/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,grahamb/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,SwinburneOnline/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,SwinburneOnline/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,djbender/canvas-lms