Add Pinephone Documentation to the Void Docs

I got void linux working on my pinephone is a slightly hacky way. I talked a bit with the maker of u-boot and p-boot that made an image with 13 distros to try out stuff on the pinephone.

The article I followed was here: https://xnux.eu/howtos/install-arch-linux-arm.html

However, this did not work as the author changed up the repos somewhat for newer stuff to be accomplished.
When I talked with him, we decided to flash the void linux aarch64 ROOTFS over one of the distros in the multi boot image ( I booted over maemo), and it does successfully boot, although I am taking the the void linux terminal login which I am not sure what I can do not (will probably attach my keyboard and trying building plasma mobile from scratch)

I think void linux would be a good distro for the pinephone as it has both musl and glibc and is rolling release.

I talked with someone else and they said they did void working by using void-mklive, but it is not clear how the general user would use that versus some of these premade images.
If we could get some step by step guide for getting void on the pinephone or a prebuilt image, that would be super sweet.

Start with the linked Arch Linux ARM article and the Void mklive approach described in the issue, then determine which PinePhone installation method is supportable. Done means providing a tested step-by-step guide or a clearly supported prebuilt image path for general users.