This file is embedded into the GRUB bootloaders at build-time.
Helps GRUB find our ShredOS volume when it cannot (Ventoy BIOS).
There is no point to put it anywhere on the USB - so don't do that.

Keep consistent with BR2_TARGET_ROOTFS_ISO9660_GRUB2_EFI_IDENT_FILE
when building any configurations that build both an ISO and the IMG.

Do not use the version file as identification file though, because
read-only ISO9660 filesystem doesn't have it (but has needed grub.cfg),
so you should always use a unique file not otherwise used for anything.

Also ensure it is in a location where users cannot delete it by accident.

Note that contrary to the GNU manual the BIOS bootloader seems to need the
explicit "configfile" directive, otherwise the Buildroot static prefix takes
precedence over the actual found volume path (which may be entirely different).
