Vendor dependencies for 0.3.0 release

vendor/bevy/examples/ecs/startup_system.rs

@@ -0,0 +1,20 @@
+//! Demonstrates a startup system (one that runs once when the app starts up).
+
+use bevy::prelude::*;
+
+fn main() {
+    App::new()
+        .add_systems(Startup, startup_system)
+        .add_systems(Update, normal_system)
+        .run();
+}
+
+/// Startup systems are run exactly once when the app starts up.
+/// They run right before "normal" systems run.
+fn startup_system() {
+    println!("startup system ran first");
+}
+
+fn normal_system() {
+    println!("normal system ran second");
+}