docs: add kroxylicious operator to the list #5262

Job	Run time
sample_operators_tests (sample-operators/tomcat-operator)	2m 50s
sample_operators_tests (sample-operators/leader-election)	3m 11s
sample_operators_tests (sample-operators/webpage)	3m 3s
sample_operators_tests (sample-operators/mysql-schema)	2m 25s
	11m 29s

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