Add note on editor_button visibility in LTI docs
Add note on editor_button visibility in LTI docs

Closes PLAT-5144

Test Plan:
Verify the Editor Button documentation page
now includes notes on the "visibility"
property.

Change-Id: I136a3171009716bf9db2ec39a67d7d00bbd9ee2c
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/217475
Tested-by: Jenkins
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Evan Battaglia <e557ffdfc4b80aab44858030b0ae5370b86cb7b1@instructure.com>
Reviewed-by: Marc Phillips <b810f855174e0bc032432310b0808df2cf714fbc@instructure.com>
QA-Review: Evan Battaglia <e557ffdfc4b80aab44858030b0ae5370b86cb7b1@instructure.com>
Product-Review: Weston Dransfield <e9203059795dc94e28a8831c65eb7869e818825e@instructure.com>

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