Confiusing output for `edgedb instance start --help`

[1st1]

Not sure what this means:

        --auto-restart    With --foreground stops server running in background. And
                          restarts the service back on exit.

[tailhook]

It is literally what it does:

1. stops server running in background
2. Runs server in foreground
3. restarts the service back when (2) exits.

This is kinda docker attach to see logs but without actually attaching. Please propose a better phrasing.

[tailhook]

I don't see too many confused users. That might mean that this function is little used, which is also fine. It was also in two stable releases, so it makes little sense to rename.