docs: mention use case for <KeepAlive> in definePageMeta

docs/content/2.guide/2.directory-structure/1.pages.md

@@ -268,7 +268,9 @@ Of course, you are welcome to define metadata for your own use throughout your a
 
 #### `keepalive`
 
-Nuxt will automatically wrap your page in [the Vue `<KeepAlive>` component](https://vuejs.org/guide/built-ins/keep-alive.html#keepalive) if you set `keepalive: true` in your `definePageMeta`. This might be useful to do, for example, in a parent route that has dynamic child routes, if you want to preserve page state across route changes. You can also set props to be passed to `<KeepAlive>` (see a full list [here](https://vuejs.org/api/built-in-components.html#keepalive)).
+Nuxt will automatically wrap your page in [the Vue `<KeepAlive>` component](https://vuejs.org/guide/built-ins/keep-alive.html#keepalive) if you set `keepalive: true` in your `definePageMeta`. This might be useful to do, for example, in a parent route that has dynamic child routes, if you want to preserve page state across route changes. 
+
+When your goal is to preserve state for parent routes use this syntax: `<NuxtPage :keepalive="{ include: 'index' }" />`. You can also set props to be passed to `<KeepAlive>` (see a full list [here](https://vuejs.org/api/built-in-components.html#keepalive)).
 
 You can set a default value for this property [in your `nuxt.config`](/api/configuration/nuxt-config#keepalive).