CacheAspectSupport checks Cache.get(key) once per invocation only

Issue: SPR-11592
Fixed SPR issue reference and aligned exception messages

Issue: SPR-11592
Update SockJS overview section and polish
Revise section explaining the flow of STOMP messages
Add doc section on configuration and performance

Issue: SPR-11450
Next development version
Revert "Next development version"

This reverts commit 4788875a4b627f615f7e496dd18ad222e981d34e.