Add stub code

docs/chapters/click_sprite.md

@@ -5,4 +5,13 @@ tags:
   - sprite
 ---
 
-# Respond to clicking on a sprite.
+# Respond to clicking on a sprite
+
+This page is a stub.
+
+```rust
+fn main() {
+    let mut app = create_app();
+    app.run();
+}
+```

docs/chapters/respond_to_key_press.md

@@ -78,7 +78,7 @@ fn test_player_responds_to_key_press() {
 fn main() {
     let mut app = create_app();
     let add_camera_fn = |mut commands: Commands| {
-        commands.spawn(Camera2d::default());
+        commands.spawn(Camera2d);
     };
     app.add_systems(Startup, add_camera_fn);
     app.add_plugins(DefaultPlugins);

docs/chapters/use_game_state.md

@@ -4,3 +4,12 @@ tags:
 ---
 
 # Use game state
+
+This page is a stub.
+
+```rust
+fn main() {
+    let mut app = create_app();
+    app.run();
+}
+```

docs/chapters/use_resources.md

@@ -4,3 +4,13 @@ tags:
 ---
 
 # Use resources
+
+This page is a stub.
+
+```rust
+fn main() {
+    let mut app = create_default_app();
+    app.add_plugins(DefaultPlugins);
+    app.run();
+}
+```

docs/chapters/use_window_title.md

@@ -5,3 +5,12 @@ tags:
 ---
 
 # Use window title
+
+This page is a stub.
+
+```rust
+fn main() {
+    let mut app = create_app();
+    app.run();
+}
+```