Put versions on documentation

[liamgsmith]

In the NextJS Auth page https://supabase.com/docs/guides/auth/server-side/nextjs?queryGroups=router&router=pages it doesn't say which versions of NextJS this approach will work with.
Prior versions of the documentation also have had this issue.

Can you please put what version of NextJS your documentation should be run against - it seems so simple a thing to not have and it makes writing applicable code very hard.

Thanks so much team!