Update README.md

[chrisvacc]

There were a couple of issues here. In order of importance:

The most important ones were around line 55 and line 72. The instructions have the user mkdir boot but then untar the Arch-Linux ARM Tarball to ~/root/

(Line 57) If you try to create a FAT filesystem while the disk is mounted, it will throw a 'resource busy' Error

(Line 59) e2fsprogs isn't a default app on the mac and has to be installed via brew.

Edit: Sorry, I just noticed this was meationed in the intro. My fault, I just scrolled right down to the instructions.

(Line 48) diskutil list Will show you the disk identifier.

Misc: I also added instructions for the popular Rock64 line of boards on macOS.

[chrisvacc]

Great guide, btw.

Edit: Actually don't pull this yet. I'm working on a solution that won't require Paragon. Also one that uses mac's built-in Utils.

I also might add a GUI solution as well.