message: fix iter_u32_digits comment
diff: @@ -3000,7 +3000,7 @@ impl BigInt {
  (self.sign, self.data.to_u64_digits())
  }
  - /// Returns an iterator of `u64` digits representation of the `BigUint` ordered least
  + /// Returns an iterator of `u32` digits representation of the `BigUint` ordered least
  /// significant digit first.
  ///
  /// # Examples
  