message: Minor doc fix to into_flat_samples
  The methods were updated in but the doc string was not missed.
diff: @@ -632,7 +632,7 @@ where
  /// Return a view on the raw sample buffer.
  ///
  - /// See `flattened` for more details.
  + /// See [`into_flat_samples`](#method.into_flat_samples) for more details.
  pub fn as_flat_samples(&self) -> FlatSamples<&[P::Subpixel]>
  where Container: AsRef<[P::Subpixel]>
  {
  