docs: remove reference to our tailnet

We've exposed teal's SSH to the outside world, so it's now possible to
use the SSH push URL for josh

README.md

···
 ```ssh-config
 # In ~/.ssh/config
 Host git.freshlybakedca.ke
-  Hostname teal
-  # ^ Pushing can currently only be done from inside our Tailscale network. We are considering solutions to this limitation
   User git
   ForwardAgent yes
 ```