Set type of argument in course settings docs
Set type of argument in course settings docs

flag = none
closes LS-3235

Test plan:
 - Run rake doc:api to build the docs
 - Visit /doc/api/courses.html#method.courses.update_settings and
   expect to see type of boolean next to
   allow_student_anonymous_discussion_topics

Change-Id: If3e0460ee6e598b5220241d8ce441d7bee506cc4
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/294403
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Robin Kuss <0b206b54367b2de0334896ea45826f0e3194bd35@instructure.com>
QA-Review: Robin Kuss <0b206b54367b2de0334896ea45826f0e3194bd35@instructure.com>
Product-Review: Jackson Howe <318c10a818c1b1f2ec50cdcb1827b2c6c5ebd7dc@instructure.com>

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