docs: optimize route higtlight (#4520)

Author: winchesHe

apps/docs/content/docs/guide/routing.mdx

@@ -86,7 +86,7 @@ Go to your `app/providers.tsx` or `app/providers.jsx` (create it if it doesn't e
 
 #### Add the `useRouter`
 
-```tsx {16}
+```tsx {15}
 // app/providers.tsx
 "use client";