fix up live assessment api docs

fixes CNVS-13441

test plan
- read the docs
- ensure they aren't as horrible as before

Change-Id: I88407c34fdd6b9260aed8576dfeda445f2ea3f87
Reviewed-on: https://gerrit.instructure.com/36212
Reviewed-by: Braden Anderson <braden@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Joel Hough <joel@instructure.com>