update en-GB translation
update en-GB translation

Change-Id: I98084751542ed1882c41bd58978a58dfb03d338d

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