chore(cli): document compatibility to be Kong 3.x #2062

Job	Run time
integration (kong:1.4.3)	1m 18s
integration (kong:1.5.1)	1m 32s
integration (kong:2.0.5)	1m 31s
integration (kong:2.1.4)	1m 30s
integration (kong:2.2.2)	1m 20s
integration (kong:2.3.3)	1m 26s
integration (kong:2.4.1)	1m 31s
integration (kong:2.5.1)	1m 42s
integration (kong:2.6.0)	1m 20s
integration (kong:2.7)	1m 30s
integration (kong:2.8)	1m 25s
integration (kong:3.0)	1m 31s
integration (kong:3.1)	1m 40s
integration (kong:3.2)	1m 44s
integration (kong:3.3)	2m 2s
integration (kong/kong:master-alpine)	1m 43s
	24m 45s

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