f - Document stale min_rbf_feerate on FeeRateBelowRbfMinimum

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jkczyz

lightning/src/ln/funding.rs

@@ -117,6 +117,14 @@ pub enum FundingContributionError {
 		max_feerate: FeeRate,
 	},
 	/// The feerate is below the minimum RBF feerate.
+	///
+	/// Note: [`FundingTemplate::min_rbf_feerate`] may be derived from an in-progress
+	/// negotiation that later aborts, leaving a stale (higher than necessary) minimum. If
+	/// this error occurs after receiving [`Event::SpliceFailed`], call
+	/// [`ChannelManager::splice_channel`] again to get a fresh template.
+	///
+	/// [`Event::SpliceFailed`]: crate::events::Event::SpliceFailed
+	/// [`ChannelManager::splice_channel`]: crate::ln::channelmanager::ChannelManager::splice_channel
 	FeeRateBelowRbfMinimum {
 		/// The requested feerate.
 		feerate: FeeRate,