Upstream has downgraded Nix to version 2.3 again which means the
`nix --extra-experimental-features` flag has disappeared from the
CLI again.

Not necessary anymore since the upgrade to 21.11

This constantly breaks the CI and there is not much use for it anyway.

Add an info how to build remotely.

Resolves #3. Feel free to reopen or file a PR ^_^

Resolves #1

Fix CI

See merge request !1

Set the enable option for auto login to `true`.

Enable auto login and leave a hint that the default account does not
require a password.