docs: release notes for the v20.3.16 release #649

Job	Run time
lint	1m 49s
build	19s
build-e2e-windows	23s
Browser Compatibility Tests	0s
e2e	0s
publish-snapshots	0s
e2e-package-managers	0s
e2e-snapshots	-1s
test	-1s
e2e-windows	0s
	2m 29s

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