docs: release notes for the v21.2.2 release #10022

Job	Run time
build	2m 14s
build-e2e-windows	2m 37s
lint	2m 2s
test	52s
Browser Compatibility Tests	49s
publish-snapshots	41s
e2e-windows (24, esbuild, 0)	19s
e2e-windows (24, esbuild, 1)	20s
e2e-windows (24, esbuild, 5)	27s
e2e-windows (24, webpack, 1)	20s
e2e-windows (24, webpack, 3)	20s
e2e-windows (24, esbuild, 3)	21s
e2e-windows (24, webpack, 0)	19s
e2e-windows (24, esbuild, 2)	21s
e2e-windows (24, webpack, 5)	22s
e2e-windows (24, webpack, 2)	20s
e2e-windows (24, esbuild, 4)	21s
e2e-windows (24, webpack, 4)	21s
e2e-package-managers	1s
e2e	1s
e2e-snapshots	1s
	13m 29s

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