@undocumented warnings when generating yard docs

fixes: CNVS-5004

When generating yard docs we get an @undocumented tag does not
exist error.  This fix changes them from @undocumented to
@note which is a valid tag.

Change-Id: I976f96d8d1230eaecc55898884fb3947d664a2d3
Reviewed-on: https://gerrit.instructure.com/29990
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Nick Cloward <ncloward@instructure.com>