f: add comments to the trimming loops

Author: tankyleo

lightning/src/events/bump_transaction/mod.rs

@@ -507,6 +507,9 @@ where
 				{
 					break;
 				}
+				// If adding this UTXO to `selected_utxos` would push us over the
+				// `max_coin_selection_weight`, remove UTXOs from the front to make room
+				// for this new UTXO.
 				while selected_utxos_weight + BASE_INPUT_WEIGHT + utxo.satisfaction_weight
 					> max_coin_selection_weight
 					&& !selected_utxos.is_empty()
@@ -534,6 +537,9 @@ where
 				);
 				return Err(());
 			}
+			// Once we've selected enough UTXOs to cover `target_amount_sat + total_fees`,
+			// we may be able to remove some small-value ones while still covering
+			// `target_amount_sat + total_fees`.
 			while !selected_utxos.is_empty()
 				&& selected_amount - selected_utxos.front().unwrap().0.output.value
 					>= target_amount_sat + total_fees - selected_utxos.front().unwrap().1