message: Expand docs for `Image::from_rgba8`.
  Resolves
diff: @@ -141,6 +141,12 @@ impl Image {
  }
  /// Creates a new `Image` from the given buffer of `u8` RGBA values.
  + ///
  + /// The pixel layout is row-major. That is,
  + /// the first 4 `u8` values make the top-left pixel in the `Image`, the
  + /// next 4 make the next pixel in the same row, and so on to the end of
  + /// the row. The next `width * 4` values make up the second row, and so
  + /// on.
  pub fn from_rgba8(
  context: &mut Context,
  width: u16,
  