Extended instructions for using `t2 root` on Windows?

@jxmot noted challenges using `t2 root` on Windows (https://forums.tessel.io/t/tessel-2-how-to-get-an-ssh-client-running-on-windows-to-work-with-a-tessel-2/3305) and wrote this great tutorial: https://github.com/jxmot/tessel-ssh-win – should we incorporate this into the t2 docs?

