fix(docs): Add window arg in splashscreen example, closes #1572

docs/guides/features/splashscreen.md

@@ -34,11 +34,11 @@ Now, your main window will be hidden and the splashscreen window will show when
 If you are waiting for your web code, you'll want to create a `close_splashscreen` [command](command).
 
 ```rust src-tauri/main.rs
-use tauri::Manager;
+use tauri::{Manager, Window};
 // Create the command:
 // This command must be async so that it doesn't run on the main thread.
 #[tauri::command]
-async fn close_splashscreen() {
+async fn close_splashscreen(window: Window) {
   // Close splashscreen
   window.get_window("splashscreen").expect("no window labeled 'splashscreen' found").close().unwrap()
   // Show main window
@@ -82,6 +82,7 @@ If you are waiting for Rust code to run, put it in the `setup` function handler
 
 ```rust src-tauri/main.rs
 use tauri::Manager;
+
 fn main() {
   tauri::Builder::default()
     .setup(|app| {