docs: Fix the hooks code in oauth getting started (#6193)
* Fix the hooks code in oauth getting started
Fixes https://github.com/nextauthjs/next-auth/issues/6192
* Apply suggestions from code review
Co-authored-by: Nico Domino <yo@ndo.dev>
Co-authored-by: Balázs Orbán <info@balazsorban.com>
Co-authored-by: Nico Domino <yo@ndo.dev>
