docs(updating): add vue router 5 migration guidance for ionic 9

docs/updating/9-0.md

@@ -238,7 +238,7 @@ For more information on migrating from React Router v5 to v6, refer to the [Reac
 
 ### Vue
 
-1. Ionic 9 supports Vue 3.0.6+. Update to the latest version of Vue:
+1. Ionic 9 supports Vue 3.5+ and Vue Router 5. Update Vue and Vue Router:
 
 ```shell
 npm install vue@latest vue-router@latest
@@ -250,6 +250,48 @@ npm install vue@latest vue-router@latest
 npm install @ionic/vue@latest @ionic/vue-router@latest
 ```
 
+#### Vue Router 5 Migration
+
+`@ionic/vue-router` now requires Vue Router v5. Vue Router v4 is no longer supported. Vue Router v5 also raises its peer requirement on Vue itself, so the minimum supported Vue version moves to `3.5.0`.
+
+Vue Router v5 is a transition release that ships no runtime breaking changes for Vue Router v4 consumers, so no application code changes are required for routes, navigation guards, or `IonRouterOutlet`. Bump the dep ranges in your app's `package.json`:
+
+```diff
+  "dependencies": {
+-   "vue": "^3.4.0",
+-   "vue-router": "^4.0.0"
++   "vue": "^3.5.0",
++   "vue-router": "^5.0.0"
+  }
+```
+
+#### Deprecation Warning for `next()` in Navigation Guards
+
+Vue Router v5 prints a deprecation warning when `next()` is called inside `beforeRouteLeave`, `beforeRouteEnter`, `beforeRouteUpdate`, or `router.beforeEach`. The callback form still works, but Vue Router v6 will remove it. Migrate to the return-value pattern:
+
+```diff
+  // Composition API
+  onBeforeRouteLeave((to, from) => {
+-   if (!confirm('Leave?')) return next(false);
+-   next();
++   if (!confirm('Leave?')) return false;
++   return true;
+  });
+```
+
+```diff
+  // Options API
+- beforeRouteLeave(to, from, next) {
+-   if (!confirm('Leave?')) return next(false);
+-   next();
++ beforeRouteLeave(to, from) {
++   if (!confirm('Leave?')) return false;
++   return true;
+  }
+```
+
+For more information on migrating from Vue Router v4 to v5, refer to the [Vue Router v4-to-v5 migration guide](https://router.vuejs.org/guide/migration/v4-to-v5.html).
+
 ### Core
 
 1. Update to the latest version of Ionic 9: