So Ubuntu mate is now an 'official' third party OS I guess: https://www.raspberrypi.org/downloads/
I'd like to install it to try it out, I know how to install using a .img file, no problem.
The problem is that I would like to install it using NOOBS instead, but Ubuntu Mate isn't a downloadable option when using NOOBS, but all the other OS's are. I like to have 2 OS's; one media player, and one regular distro, otherwise I would just not use NOOBS.
I've looked at the README for NOOBS here: https://github.com/raspberrypi/noobs#how-to-create-a-custom-os-version
but I can't quite figure out how to do it. I figured out how to make the boot.tar.xz (from the ubuntu .img file) but I don't know how to make the root.tar.xz.
If someone could show me how to get NOOBS to install both Ubuntu Mate and OSMC on the same SD, that would be great.