add docs around the course_section LiveEvents
add docs around the course_section LiveEvents

Change-Id: I176a0b13c7b397890c18d2b06f944458535d466d
Reviewed-on: https://gerrit.instructure.com/199748
Tested-by: Jenkins
Reviewed-by: Clint Furse <b31c824c483447b2438702c2da6f729b3ebb9b50@instructure.com>
QA-Review: Ethan Knapp <1d1e44f931ae3e900bcc509316bb99104bed6d49@instructure.com>
Product-Review: Ethan Knapp <1d1e44f931ae3e900bcc509316bb99104bed6d49@instructure.com>

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