docs: release notes for the v21.1.3 release #1626

Job	Run time
list	21s
workflow (devkit-core-tests)	26s
workflow (build-unit-tests)	26s
workflow (build-cli)	23s
workflow (modules-builder-tests)	25s
workflow (devkit-core-tests-rerun)	26s
	2m 27s

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