NEWS: try to fix old entry regarding KERNEL_INSTALL_LAYOUT
The old text was simply wrong, we used to read $layout from
/etc/kernel/install.conf and the machine ID from
$KERNEL_INSTALL_MACHINE_ID from /etc/machine-info. Correct that.
Apparently KERNEL_INSTALL_MACHINE_ID was already known back in v235
times, hence don't mention it anymore.
it's kinda weird retro-fixing these NEWS entries, given we deprecate
them again, but I couldn't let this really incorrect stuff be.