docs(merging_objects): add missing structs in example

docs/en/src/merging_objects.md

@@ -25,6 +25,9 @@ Instead, the `#[derive(MergedObject)]` macro allows you to split an object's res
 **Note:** This works for queries and mutations. For subscriptions, see "Merging Subscriptions" below.
 
 ```rust
+#[derive(Default)]
+struct UserQuery;
+
 #[Object]
 impl UserQuery {
     async fn users(&self) -> Vec<User> {
@@ -32,6 +35,9 @@ impl UserQuery {
     }
 }
 
+#[derive(Default)]
+struct MovieQuery;
+
 #[Object]
 impl MovieQuery {
     async fn movies(&self) -> Vec<Movie> {

docs/zh-CN/src/merging_objects.md

@@ -25,6 +25,9 @@ impl MyObject {
 **提示:** 每个`#[Object]`需要一个唯一的名称，即使在一个`MergedObject`内，所以确保每个对象有单独的名称。
 
 ```rust
+#[derive(Default)]
+struct UserQuery;
+
 #[Object]
 impl UserQuery {
     async fn users(&self) -> Vec<User> {
@@ -32,6 +35,9 @@ impl UserQuery {
     }
 }
 
+#[derive(Default)]
+struct MovieQuery;
+
 #[Object]
 impl MovieQuery {
     async fn movies(&self) -> Vec<Movie> {