Mention how to use gokrazy as a Tailscale subnet router (≥ v1.64) and how to sign in with Tailscale SSH.
fixes https://github.com/gokrazy/gokrazy/issues/209 related to https://github.com/tailscale/tailscale/pull/10273
related to https://github.com/gokrazy/gokrazy/issues/147