doc: mention containerd requirement #1572

Job	Run time
matrix-prep-bazelversion	4s
matrix-prep-os	1s
test (ubuntu-latest, 7.1.1, ., true)	5m 18s
test (ubuntu-latest, 7.1.1, ., false)	2m 20s
test (ubuntu-latest, 7.1.1, e2e/wasm, false)	2m 7s
test (ubuntu-latest, 7.1.1, e2e/smoke, true)	24s
test (ubuntu-latest, 7.1.1, e2e/smoke, false)	31s
test (ubuntu-latest, 7.1.1, e2e/assertion, true)	3m 7s
test (ubuntu-latest, 6.4.0, ., true)	5m 46s
test (ubuntu-latest, 6.4.0, ., false)	2m 47s
test (ubuntu-latest, 6.4.0, e2e/wasm, false)	26s
test (ubuntu-latest, 6.4.0, e2e/smoke, true)	19s
test (ubuntu-latest, 6.4.0, e2e/smoke, false)	11s
test (ubuntu-latest, 6.4.0, e2e/assertion, true)	2m 49s
test (macos-13, 7.1.1, ., true)	7m 26s
test (macos-13, 7.1.1, ., false)	5m 14s
test (macos-13, 7.1.1, e2e/smoke, true)	43s
test (macos-13, 7.1.1, e2e/smoke, false)	41s
	40m 14s

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