fix(docs): update error type in notFound function description (#77503)

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### What?

* Update the documentation to reflect the current named exception.

### Why?

* The code was updated, but the documentation was not.

### How?

* Replace outdated information in the markdown file with the correct
details.

Author: Bernardoow

docs/01-app/04-api-reference/04-functions/not-found.mdx

@@ -7,7 +7,7 @@ The `notFound` function allows you to render the [`not-found file`](/docs/app/ap
 
 ## `notFound()`
 
-Invoking the `notFound()` function throws a `NEXT_NOT_FOUND` error and terminates rendering of the route segment in which it was thrown. Specifying a [**not-found** file](/docs/app/api-reference/file-conventions/not-found) allows you to gracefully handle such errors by rendering a Not Found UI within the segment.
+Invoking the `notFound()` function throws a `NEXT_HTTP_ERROR_FALLBACK;404` error and terminates rendering of the route segment in which it was thrown. Specifying a [**not-found** file](/docs/app/api-reference/file-conventions/not-found) allows you to gracefully handle such errors by rendering a Not Found UI within the segment.
 
 ```jsx filename="app/user/[id]/page.js"
 import { notFound } from 'next/navigation'