Update wording to remove beta FUD and keep evergreen (#42337)

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

docs/getting-started.md

@@ -2,7 +2,7 @@
 description: Get started with Next.js in the official documentation, and learn more about all our features!
 ---
 
-> The beta version of Next.js 13 has been [publicly released](https://nextjs.org/blog/next-13), [read the new docs here](https://beta.nextjs.org/docs).
+> Next.js 13 has been [publicly released](https://nextjs.org/blog/next-13), [read the docs here](https://beta.nextjs.org/docs).
 
 # Getting Started