docs: explain that +layout files do not affect +server.js (#13152)

closes #12401

Author: teemingc

documentation/docs/20-core-concepts/10-routing.md

@@ -53,7 +53,7 @@ Pages can receive data from `load` functions via the `data` prop.
 > [!LEGACY]
 > In Svelte 4, you'd use `export let data` instead
 
-> [!NOTE] Note that SvelteKit uses `<a>` elements to navigate between routes, rather than a framework-specific `<Link>` component.
+> [!NOTE] SvelteKit uses `<a>` elements to navigate between routes, rather than a framework-specific `<Link>` component.
 
 ### +page.js
 
@@ -302,6 +302,8 @@ If an error is thrown (either `error(...)` or an unexpected error), the response
 
 > [!NOTE] When creating an `OPTIONS` handler, note that Vite will inject `Access-Control-Allow-Origin` and `Access-Control-Allow-Methods` headers — these will not be present in production unless you add them.
 
+> [!NOTE] `+layout` files have no effect on `+server.js` files. If you want to run some logic before each request, add it to the server [`handle`](hooks#Server-hooks-handle) hook.
+
 ### Receiving data
 
 By exporting `POST`/`PUT`/`PATCH`/`DELETE`/`OPTIONS`/`HEAD` handlers, `+server.js` files can be used to create a complete API: