Describe expected life cycle management of next-links inside 11.2.4.7 Server-Driven Paging

We should say something about what to expect when a next-link expires (as we are storage model agnostic and cannot assume, that this
will always be a reconstructable query).

This might apply to other opaque tokens that act as URLs to retrievable resources.

As of now we do not describe this in any detail.

A common scenario from the interactive browsing would be a client stepping through a paged result set and "bookmarking" a certain page for later retrieval. This might be due to relevance of the pages content or as a planned re-entrance point for resuming some analysis of the result set (both motivations assuming the result set is somewhat constant or only slowly changing).