FR: clarify tailscale status terminology

### What are you trying to do?

Running `tailscale status` shows: `Tailscale is stopped.`

However, tailscale's action commands are `up` and `down`, not `start` and `stop`.

### How should we solve this?

There are a few ways of solving this.

1. Add more info on the end of that printout saying `To start tailscale, run 'tailscale up'`
2. Use the same terminology as the actions and print `Tailscale is down.` so the user knows to alter it they need to bring it `up`

### What is the impact of not solving this?

Just general polish/user experience improvement.

### Anything else?

_No response_