Update docs about graceful shutdown

documentation/docs/graceful-shutdown.md

@@ -1,41 +1,43 @@
-# Graceful Shutdown
-
-When the Flutter app is closed, the entire `tokio` runtime on the Rust side will be terminated automatically. However, you might need to run some finalization code in Rust before the app closes. This might involve saving files or disposing of resources. To achieve this, you can call `finalizeRust()` in Dart to terminate all Rust tasks before closing the Flutter app.
-
-```dart title="lib/main.dart"
-import 'dart:ui';
-import 'package:flutter/material.dart';
-import './messages/generated.dart';
-...
-class MyApp extends StatefulWidget {
-  const MyApp({super.key});
-
-  @override
-  State<MyApp> createState() => _MyAppState();
-}
-
-class _MyAppState extends State<MyApp> {
-  final _appLifecycleListener = AppLifecycleListener(
-    onExitRequested: () async {
-      // Terminate Rust tasks before closing the Flutter app.
-      await finalizeRust();
-      return AppExitResponse.exit;
-    },
-  );
-
-  @override
-  void dispose() {
-    _appLifecycleListener.dispose();
-    super.dispose();
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    return MaterialApp(
-      title: 'Some App',
-      home: MyHomePage(),
-    );
-  }
-}
-...
-```
+# Graceful Shutdown
+
+When the Flutter app is closed, the entire `tokio` async runtime on the Rust side will be terminated automatically.
+
+When using Rinf, the lifetime of the `tokio` runtime follows that of the Dart runtime. This behavior is different from typical `tokio` executables where its async runtime lives throughout the `main()` function of Rust.
+
+In some cases, you might need to run some finalization code in Rust before the app closes. This might involve saving files or disposing of resources. To achieve this, you can use Flutter's `AppLifecycleListener` to run something or to get user confirmation before closing the Flutter app.
+
+```dart title="lib/main.dart"
+import 'dart:ui';
+import 'package:flutter/material.dart';
+...
+class MyApp extends StatefulWidget {
+  const MyApp({super.key});
+
+  @override
+  State<MyApp> createState() => _MyAppState();
+}
+
+class _MyAppState extends State<MyApp> {
+  final _appLifecycleListener = AppLifecycleListener(
+    onExitRequested: () async {
+      // Do something here before the app is exited.
+      return AppExitResponse.exit;
+    },
+  );
+
+  @override
+  void dispose() {
+    _appLifecycleListener.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Some App',
+      home: MyHomePage(),
+    );
+  }
+}
+...
+```