add example

assets/examples/ruby/current_entity.rb

@@ -0,0 +1,3 @@
+get_name(Bevy::Entity.current).and_then do |name|
+  print(name)
+end

examples/ruby/current_entity.rs

@@ -0,0 +1,25 @@
+use bevy::prelude::*;
+use bevy_scriptum::prelude::*;
+use bevy_scriptum::runtimes::ruby::prelude::*;
+
+fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .add_scripting::<RubyRuntime>(|runtime| {
+            runtime.add_function(
+                String::from("get_name"),
+                |In((BevyEntity(entity),)): In<(BevyEntity,)>, names: Query<&Name>| {
+                    names.get(entity).unwrap().to_string()
+                },
+            );
+        })
+        .add_systems(Startup, startup)
+        .run();
+}
+
+fn startup(mut commands: Commands, assets_server: Res<AssetServer>) {
+    commands.spawn((
+        Name::from("MyEntityName"),
+        Script::<RubyScript>::new(assets_server.load("examples/ruby/current_entity.rb")),
+    ));
+}