docs: add link to layers from pages/ docs (#20976)

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

@@ -361,3 +361,31 @@ function navigate(){
 As your app gets bigger and more complex, your routing might require more flexibility. For this reason, Nuxt directly exposes the router, routes and router options for customization in different ways.
 
 :ReadMore{link="/docs/guide/going-further/custom-routing"}
+
+## Multiple pages directories
+
+By default, all your pages should be in one `pages` directory at the root of your project.
+However, you can use Layers to create groupings of your app's pages.
+
+Example:
+
+```bash
+-| nuxt.config.ts
+-| some-app/
+---| nuxt.config.ts
+---| pages
+-----| app-page.vue
+```
+
+```ts
+// some-app/nuxt.config.ts
+export default defineNuxtConfig({
+})
+
+// nuxt.config.ts
+export default defineNuxtConfig({
+  extends: ['./some-app'],
+})
+```
+
+:ReadMore{link="/docs/guide/going-further/layers"}