f update docs

Author: TheBlueMatt

lightning-invoice/src/utils.rs

@@ -512,8 +512,9 @@ fn _create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_has
 /// * Always select the channel with the highest inbound capacity per counterparty node
 /// * Prefer channels with capacity at least `min_inbound_capacity_msat` and where the channel
 ///   `is_usable` (i.e. the peer is connected).
-/// * If any public channel exists, the returned `RouteHint`s will be empty, and the sender will
-///   need to find the path by looking at the public channels instead
+/// * If any public channel exists, only public [`RouteHint`]s will be returned,
+/// * If any public, announced channel exists, no [`RouteHint`]s will be returned, as the sender
+///   is expected to find the path by looking at the public channels instead.
 fn filter_channels<L: Deref>(
 	channels: Vec<ChannelDetails>, min_inbound_capacity_msat: Option<u64>, logger: &L
 ) -> Vec<RouteHint> where L::Target: Logger {