https://jamesdefabia.github.io/docs/user-guide/kubectl/kubectl_label/
⋊> /m/c/U/yuta kubectl label namespace test-20210401-01 app=test 02:50:42
namespace/test-20210401-01 labeled
⋊> /m/c/U/yuta kubectl describe namespace test-20210401-01 02:50:52
Name: test-20210401-01
Labels: app=test
unhealthy=true
Annotations: <none>
Status: Active
No resource quota.
No LimitRange resource.
⋊> /m/c/U/yuta
