message: Improve documentation for gif encoder constructor
diff: @@ -416,7 +416,7 @@ pub struct GifEncoder<W: Write> {
  }
  impl<W: Write> GifEncoder<W> {
  - /// Creates a new GIF encoder.
  + /// Creates a new GIF encoder with a speed of 1. This prioritizes quality over performance at any cost.
  pub fn new(w: W) -> GifEncoder<W> {
  Self::new_with_speed(w, 1)
  }
  