message: add docs to encoder wrapper
diff: @@ -368,10 +368,16 @@ pub fn write_buffer(
  // TODO is this struct and trait actually used anywhere?
  +/// A thin wrapper that implements `ImageEncoder` for OpenEXR images. Will behave like `image::codecs::openexr::write_buffer`.
  #[derive(Debug)]
  pub struct Encoder<W> (W);
  -impl<W> Encoder<W> { pub fn new(write: W) -> Self {Self(write)} }
  +impl<W> Encoder<W> {
  + /// Create an `ImageEncoder`. Does not write anything yet. Will behave like `image::codecs::openexr::write_buffer`.
  + // function for future backwards-compatibility
  + pub fn new(write: W) -> Self {Self(write)}
  +}
  impl<W> ImageEncoder for Encoder<W> where W: Write /*+ Seek*/ {
  + /// Writes the complete image. Behaves just like `image::codecs::openexr::write_buffer`.
  fn write_image(self, buf: &[u8], width: u32, height: u32, color_type: ColorType) -> ImageResult<()> {
  write_buffer(self.0, buf, width, height, color_type)
  }
  