docs: release notes for the v21.1.1 release #1573

Job	Run time
list	26s
workflow (devkit-core-tests-rerun)	31s
workflow (modules-builder-tests)	25s
workflow (devkit-core-tests)	25s
workflow (build-unit-tests)	26s
workflow (build-cli)	27s
	2m 40s

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