docs: Replace code of conduct with CNCF COC reference #7185

Job	Run time
docs	1m 5s
image_tags	1s
gomod	55s
lint	3m 38s
build (controller)	2m 27s
build (kanctl)	2m 26s
test (test)	11m 19s
build (kando)	2m 16s
test (integration-test)	8m 5s
test (helm-test)	3m 8s
reno_lint	39s
release	0s
release_example_docker_images	0s
	35m 59s

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