docs(ppr): remove v14 PPR config description (#71592)
# Description
Removed the v14 mention [PPR
docs](https://nextjs.org/docs/canary/app/api-reference/next-config-js/ppr)
at #71498.
Then also delete that from related [Partial Prerendering
docs](https://nextjs.org/docs/canary/app/api-reference/next-config-js/ppr).
### Improving Documentation
- [x] Run `pnpm prettier-fix` to fix formatting issues before opening
the PR.
- [x] Read the Docs Contribution Guide to ensure your contribution
follows the docs guidelines:
https://nextjs.org/docs/community/contribution-guide
x-ref: docs(ppr): remove v14 mention for ppr #71498
Co-authored-by: JJ Kasper <jj@jjsweb.site>
