Commit 7ce1d9ce09 ("build: artifacts add dependency for built images")
now makes sure that sysupgrade and initramfs images are available at
the stage that artifacts are created.
Allow making use of that with a new build command 'append-image' to
be used in artifacts.
See the next commit for an example.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: maurerr <mariusd84@gmail.com>