chore: improve doc comments

Signed-off-by: Gregory Hill <[email protected]>

bitcoin/src/electrs/mod.rs

@@ -246,6 +246,9 @@ impl ElectrsClient {
         Ok(txs)
     }
 
+    /// Returns the *largest* payment to the `address` which is
+    /// greater than or equal to the specified `amount` and contains
+    /// an `OP_RETURN` output with `data`.
     pub(crate) async fn get_tx_for_op_return(
         &self,
         address: Address,

bitcoin/src/light/mod.rs

@@ -257,6 +257,7 @@ impl BitcoinCoreApi for BitcoinLight {
                 }
             });
 
+        // clear the witnesses for fee estimation
         existing_transaction
             .input
             .iter_mut()

bitcoin/src/light/wallet.rs

@@ -353,7 +353,7 @@ impl Wallet {
             log::info!("Found utxo: {}", utxo.outpoint.txid);
 
             if prev_txid.contains(&utxo.outpoint.txid) {
-                // skip if trying to spend previous tx (RBF)
+                // skip if trying to spend from the tx we are replacing
                 continue;
             }