message: remove forced instance src + docs instance drawing
diff: @@ -406,7 +406,7 @@ impl<'a> InternalCanvas<'a> {
  transform: (self.transform
  * glam::Mat4::from(
  // image scaling is non-sensical for instance array itself as the image scaling is applied locally (see below)
  - DrawUniforms::from_param(&param.src(Rect::one()), None).transform,
  + DrawUniforms::from_param(&param, None).transform,
  ))
  .into(),
  color: mint::Vector4::<f32> {
  @@ -416,7 +416,8 @@ impl<'a> InternalCanvas<'a> {
  w: param.color.a,
  },
  // this is the actual image scale that we apply in the vertex shader.
  - // we can't apply this when we first convert the instance array drawparams because we don't know the image size yet.
  + // we can't apply this when we first convert the instance array drawparams because we don't know the image size at the time the user inserts the drawparams.
  + // we also can't apply image scaling in the global instance transform as it *must* be applied in local space.
  scale: if scale {
  glam::Vec2::new(
  instances.image.width() as f32,
  