Constant DEFAULT_RELAY_CANDIDATES 

const DEFAULT_RELAY_CANDIDATES: &[&str];

Hard-coded candidates for default relays. In the future, we want to use it during onboarding; note that before onboarding automatically on any of these, we need to ask the admins whether their relay is able to handle this. For now, this is just the first 6 relays from chatmail.at/relays.