update ar translation
update ar translation

Change-Id: Ie71656612cc385a7e54b4c3a91f3a92ced211fbe
Reviewed-on: https://gerrit.instructure.com/210333
Tested-by: Jenkins

instructure/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms