spec: update assignments controller for post policies
spec: update assignments controller for post policies

Change-Id: Ibad4b7e26d5da4caa73ab57bc7ed36d885b7f9f4
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/229605
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>
QA-Review: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>
Product-Review: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>

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