Update docs for scaling_mode field of Orthographic projection (#9297)

# Objective

This PR updates the name of the enum variant used in the docs for
`OrthographicProjection`.

## Solution

- Change the outdated 'WindowScale` to `WindowSize`.

crates/bevy_render/src/camera/projection.rs

@@ -227,7 +227,7 @@ pub struct OrthographicProjection {
  pub viewport_origin: Vec2,
  /// How the projection will scale when the viewport is resized.
  ///
- /// Defaults to `ScalingMode::WindowScale(1.0)`
+ /// Defaults to `ScalingMode::WindowSize(1.0)`
  pub scaling_mode: ScalingMode,
  /// Scales the projection in world units.
  ///