update string in SIS text

fixes CNVS-13991

test plan
 - specs should pass

Change-Id: Ie689f634e5ec51f85e07bdd4b1af21a311af97ad
Reviewed-on: https://gerrit.instructure.com/37328
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ken Romney <kromney@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>
Product-Review: Dana Danger <dana@instructure.com>