remove point light from sessions example and other small changes

Signed-off-by: Schmarni <marnistromer@gmail.com>

crates/bevy_openxr/examples/sessions.rs

@@ -10,6 +10,7 @@ fn main() {
         .add_plugins(bevy_xr_utils::hand_gizmos::HandGizmosPlugin)
         .add_systems(Startup, setup)
         .add_systems(Update, handle_input)
+        .insert_resource(AmbientLight::default())
         .run();
 }
 
@@ -62,15 +63,6 @@ fn setup(
         transform: Transform::from_xyz(0.0, 0.5, 0.0),
         ..default()
     });
-    // light
-    commands.spawn(PointLightBundle {
-        point_light: PointLight {
-            shadows_enabled: true,
-            ..default()
-        },
-        transform: Transform::from_xyz(4.0, 8.0, 4.0),
-        ..default()
-    });
     commands.spawn(Camera3dBundle {
         transform: Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
         ..default()