Vendor dependencies for 0.3.0 release

vendor/bevy/examples/app/thread_pool_resources.rs

@@ -0,0 +1,12 @@
+//! This example illustrates how to customize the thread pool used internally (e.g. to only use a
+//! certain number of threads).
+
+use bevy::prelude::*;
+
+fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins.set(TaskPoolPlugin {
+            task_pool_options: TaskPoolOptions::with_num_threads(4),
+        }))
+        .run();
+}