documentation/release: Update release checklist
Sync checklist with release template; add new heading for paragraph
on pushing the signed tag to make it stand out.
Change-Id: Id49b3f38d3501382b7fb7ac791190c0cacd58a11
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84034
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>