f describe errors in funding_transaction_signed

Author: dunxen

lightning/src/ln/channelmanager.rs

@@ -5925,6 +5925,15 @@ where
 	///  will prevent the funding transaction from being relayed on the bitcoin network and hence being
 	///  confirmed.
 	/// </div>
+	///
+	/// Returns [`ChannelUnavailable`] when a channel is not found or an incorrect
+	/// `counterparty_node_id` is provided.
+	///
+	/// Returns [`APIMisuseError`] when a channel is not in a state where it is expecting funding
+	/// signatures.
+	/// 
+	/// [`ChannelUnavailable`]: APIError::ChannelUnavailable
+	/// [`APIMisuseError`]: APIError::APIMisuseError
 	pub fn funding_transaction_signed(
 		&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey, transaction: Transaction,
 	) -> Result<(), APIError> {