update en-GB translation
update en-GB translation

Change-Id: I54ca6847e6d4972bda853ae95813458b1bb53368

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