Function discovery_relay_options 

pub fn discovery_relay_options() -> RelayOptions

Relay options for a Discovery Relay (see state::DISCOVERY_RELAYS): the same GOSSIP|PING targeted-only isolation as Community relays — reachable via fetch_events_from / send_event_to, invisible to pool-wide DM/profile ops. An overlap with a user relay keeps the user’s READ+WRITE flags (add_relay no-ops on an already-pooled url).