docs: improve docs around geolocation and IP headers (#59719)
Based on feedback from https://github.com/vercel/next.js/issues/47793, I
made some improvements around the geolocation docs. Specifically around
`request.ip`, `request.geo`, and how to access these values. I noticed
there was a bit of a divergence, as some of the `NextRequest` and
`NextResponse` docs were split out for the App Router section, but not
all.
This PR finishes that swing by removing the previous catch-all for
`next/server` in the Pages Router docs and splits them into individual
docs pages.
Wrote a lil' thread about this:
https://twitter.com/leeerob/status/1736543599339172121
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Co-authored-by: Delba de Oliveira <32464864+delbaoliveira@users.noreply.github.com>
