Update QueryRecorder documentation

What does this MR do?

In &3873 (closed), we worked on fixing some end-points and providing the means to handle duplicated CACHE SQL calls.

This MR updates the documentation for QueryRecorder, on how to enable Sql caching in specs and to include cached queries in QueryRecorder. Provides a link to Merge request performance guidelines - Cached queries documentation introduced in !46367 (merged).

Related issues

#259004 (closed)

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