message: explained what `clear` does in Canvas docs
diff: @@ -43,6 +43,8 @@ pub struct Canvas {
  impl Canvas {
  /// Create a new [Canvas] from an image. This will allow for drawing to a single color image.
  ///
  + /// `clear` will set the image initially to the given color, if a color is provided, or keep it as is, if it's `None`.
  + ///
  /// The image must be created for Canvas usage, i.e. [Image::new_canvas_image()], or [ScreenImage], and must only have a sample count of 1.
  #[inline]
  pub fn from_image(
  @@ -92,6 +94,8 @@ impl Canvas {
  }
  /// Create a new [Canvas] that renders directly to the window surface.
  + ///
  + /// `clear` will set the image initially to the given color, if a color is provided, or keep it as is, if it's `None`.
  pub fn from_frame(gfx: &impl Has<GraphicsContext>, clear: impl Into<Option<Color>>) -> Self {
  let gfx = gfx.retrieve();
  // these unwraps will never fail
  