docs: simplify and streamline v8 release notes #521

Job	Run time
list-packages	3s
tests (ubuntu-latest, 20, redis-smq-common)	3m 7s
tests (ubuntu-latest, 20, redis-smq-web-ui)	57s
tests (ubuntu-latest, 20, redis-smq-rest-api)	3m 1s
tests (ubuntu-latest, 20, redis-smq)	10m 29s
	17m 37s

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