update en-GB translation
update en-GB translation

Change-Id: I7590b9e7183feecb89ed61d2f60c4d4b6b129919

venturehive/canvas-lms,HotChalk/canvas-lms,grahamb/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,HotChalk/canvas-lms,sfu/canvas-lms,fronteerio/canvas-lms,venturehive/canvas-lms,redconfetti/canvas-lms,SwinburneOnline/canvas-lms,grahamb/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,SwinburneOnline/canvas-lms,redconfetti/canvas-lms,djbender/canvas-lms,redconfetti/canvas-lms,SwinburneOnline/canvas-lms,sfu/canvas-lms,roxolan/canvas-lms,SwinburneOnline/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,fronteerio/canvas-lms,roxolan/canvas-lms,fronteerio/canvas-lms,HotChalk/canvas-lms,HotChalk/canvas-lms,redconfetti/canvas-lms,roxolan/canvas-lms,sfu/canvas-lms,fronteerio/canvas-lms,roxolan/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms