add elbe-init section and switch to armhf

Signed-off-by: Manuel Traut <manut@linutronix.de>
docs: add new graphics

to visualize the components of elbe

Signed-off-by: Manuel Traut <manut@linutronix.de>
elbe chroot: fix missing userinterpr

The userinterpr wasn't available during BuildEnv construction if the rfs was
already debootstrapped.

This was triggered by 'elbe chroot':

root@elbe-daemon:~# elbe chroot /opt/elbe/build
work on existing rfs
running cmd +chroot /opt/elbe/build/chroot debconf-set-selections <
/opt/elbe/build/chroot/opt/elbe/preseed.txt+
------------------------------------------------------------------------------
chroot: failed to run command `debconf-set-selections': No such file or directory
------------------------------------------------------------------------------
...
    raise CommandError(cmd, ret)
elbepack.shellhelper.CommandError

Signed-off-by: Manuel Traut <manut@linutronix.de>