docs: Add helper makefile

It worked for me on latest ubuntu,
and can adapter for other distros

Forwarded: https://booting.oniroproject.org/distro/oniro/-/merge_requests/375
Relate-to: https://git.ostc-eu.org/OSTC/OHOS/meta-ohos/-/merge_requests/235


Signed-off-by: Philippe Coval <philippe.coval@huawei.com>