Make psbt mod public and add required docs

src/psbt/mod.rs

@@ -9,11 +9,17 @@
 // You may not use this file except in accordance with one or both of these
 // licenses.
 
+//! Additional functions on the `rust-bitcoin` `PartiallySignedTransaction` structure.
+
 use crate::FeeRate;
 use bitcoin::util::psbt::PartiallySignedTransaction as Psbt;
 use bitcoin::TxOut;
 
+// TODO upstream the functions here to `rust-bitcoin`?
+
+/// Trait to add functions to extract utxos and calculate fees.
 pub trait PsbtUtils {
+    /// Get the `TxOut` for the specified input index, if it doesn't exist in the PSBT `None` is returned.
     fn get_utxo_for(&self, input_index: usize) -> Option<TxOut>;
 
     /// The total transaction fee amount, sum of input amounts minus sum of output amounts, in Sats.