docs: mention callbacks (nuxt-modules#1931)

docs/content/2.guide/2.runtime-hooks.md

@@ -2,6 +2,12 @@
 
 Nuxt i18n module exposes some [runtime hooks](https://nuxt.com/docs/guide/going-further/hooks#app-hooks-runtime) as callbacks that you can use to perform specific tasks that depend on the app's language.
 
+::alert{type="warning"}
+
+For v8.0.0-beta.10 and below, please refer to [callbacks](https://i18n.nuxtjs.org/callbacks/) and [configuration](https://i18n.nuxtjs.org/options-reference#onbeforelanguageswitch).
+
+::
+
 ---
 
 **Nuxt i18n module** exposes some callbacks that you can use to perform specific tasks that depend on the app's language.