Makes sis import descriptions all visible to NVDA

fixes: SIS-624

Test-Plan
--With SIS Import enabled--
1.) Navigate to sis import page in accounts/self
--Using NVDA--
2.) Verify that both descriptions are read

Change-Id: I9cc4eca38f0e6eedb9e7a3e5f5ad200ce6f5921e
Reviewed-on: https://gerrit.instructure.com/43959
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Duane Johnson <duane@instructure.com>
Reviewed-by: Nick Houle <nhoule@instructure.com>
QA-Review: Nathan Rogowski <nathan@instructure.com>
Product-Review: Cosme Salazar <cosme@instructure.com>