Docs: should clarify whether we can call redirect within generateMetadata

### What is the documentation issue? It is unclear whether `redirect`, `permanentRedirect`, and `notFound` can be called from `generateMetadata`. * [permanentRedirect](https://nextjs.org/docs/app/api-reference/functions/permanentRedirect): “permanentRedirect can be used in Server Components, Client Components, [Route Handlers](https://nextjs.org/docs/app/api-reference/file-conventions/route), and [Server Actions](https://nextjs.org/docs/app/getting-started/updating-data)”. No mention of `generateMetadata` so it sounds like it is prohibited. * [redirect](https://nextjs.org/docs/app/api-reference/functions/redirect): “redirect can be used in [Server Components](https://nextjs.org/docs/app/getting-started/server-and-client-components), [Route Handlers](https://nextjs.org/docs/app/api-reference/file-conventions/route), and [Server Actions](https://nextjs.org/docs/app/getting-started/updating-data).” No mention of `generateMetadata` so it sounds like it is prohibited. Also does not include Client Components although there is an example of client component below. * [notFound](https://nextjs.org/docs/app/api-reference/functions/not-found) just says to use it “within a route segment”; does not say specifically where. * [generateMetadata](https://nextjs.org/docs/app/api-reference/functions/generate-metadata) says “The [redirect()](https://nextjs.org/docs/app/api-reference/functions/redirect) and [notFound()](https://nextjs.org/docs/app/api-reference/functions/not-found) Next.js methods can also be used inside generateMetadata.”, contradicting the `redirect` documentation. Also no mention of `permanentRedirect`. I tested a basic page.tsx: ``` import { redirect } from "next/navigation"; import type { Metadata } from 'next'; export async function generateMetadata(): Promise<Metadata> { await new Promise(resolve => setTimeout(resolve, 1000)) redirect('/generate-metadata-redirect'); } export default async function Page() { await new Promise(resolve => setTimeout(resol…