MFC r364725, r364726

r364725 | imp | 2020-08-24 13:35:15 -0600 (Mon, 24 Aug 2020) | 9 lines

Change the resume notification event from 'kern' to 'kernel'

We have both a system of 'kern' and of 'kernel'. Prefer the latter and
convert this notification to use 'kernel' instead of 'kern'. As a
transition period, continue to also generate the 'kern' notification
until sometime after FreeBSD 13 is branched.

r364726 | imp | 2020-08-24 13:35:27 -0600 (Mon, 24 Aug 2020) | 4 lines

Document the kern -> kernel name change for resume events.

Relnotes: YES