[k8s][docs] Add feature cards for users and admins #14742

Job	Run time
python-test (3.8, tests/unit_tests)	6m 13s
python-test (3.8, tests/test_api.py)	3m 57s
python-test (3.8, tests/test_cli.py)	4m 25s
python-test (3.8, tests/test_config.py)	3m 45s
python-test (3.8, tests/test_global_user_state.py)	3m 45s
python-test (3.8, tests/test_jobs.py)	4m 48s
python-test (3.8, tests/test_list_accelerators.py)	4m 11s
python-test (3.8, tests/test_optimizer_dryruns.py)	6m 1s
python-test (3.8, tests/test_optimizer_random_dag.py)	4m 25s
python-test (3.8, tests/test_storage.py)	3m 42s
python-test (3.8, tests/test_wheels.py)	3m 48s
python-test (3.8, tests/test_jobs_and_serve.py)	3m 44s
python-test (3.8, tests/test_yaml_parser.py)	3m 46s
	56m 30s

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