update prefetching jsdoc & documentation (#68047)
Clarifies that static vs dynamic resources now influence the static /
dynamic staleTime that is used which should hopefully be more intuitive.
Reference PR:
- https://github.com/vercel/next.js/pull/67868
Also updates the JSDoc for `<Link />` since it was fairly out of date
and lacking any info about app router behavior.
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Co-authored-by: Delba de Oliveira <32464864+delbaoliveira@users.noreply.github.com>
