kubeadm: fix the help msg for `kubeadm init phase upload-certs`
kubeadm: fix the help msg for `kubeadm init phase upload-certs`

The phase `kubeadm init phase upload-certs` intends to be used if
secret "kubeadm-certs" is expired and deleted.

But the help msg was saying this command cannot run on its own.

It's fine to run this command on its own to upload local certs to secret.

Signed-off-by: Dave Chen <3fbbe9d8910afe5176d6dd2fc1de9e5729a30247@arm.com>

PiotrProkop/kubernetes,k82cn/kubernetes,GulajavaMinistudio/kubernetes,deads2k/kubernetes,olivierlemasle/kubernetes,soltysh/kubernetes,jackfrancis/kubernetes,soltysh/kubernetes,liggitt/kubernetes,mosoft521/kubernetes,k82cn/kubernetes,lojies/kubernetes,k82cn/kubernetes,jessfraz/kubernetes,matthyx/kubernetes,olivierlemasle/kubernetes,gnufied/kubernetes,warmchang/kubernetes,MikeSpreitzer/kubernetes,BenTheElder/kubernetes,gnufied/kubernetes,BenTheElder/kubernetes,matthyx/kubernetes,jackfrancis/kubernetes,jsafrane/kubernetes,mahak/kubernetes,soltysh/kubernetes,jessfraz/kubernetes,gnufied/kubernetes,warmchang/kubernetes,ping035627/kubernetes,jsafrane/kubernetes,jsafrane/kubernetes,soltysh/kubernetes,kevin-wangzefeng/kubernetes,gnufied/kubernetes,mkumatag/kubernetes,carlory/kubernetes,olivierlemasle/kubernetes,kubernetes/kubernetes,thockin/kubernetes,ping035627/kubernetes,lojies/kubernetes,k82cn/kubernetes,gnufied/kubernetes,kevin-wangzefeng/kubernetes,jackfrancis/kubernetes,liggitt/kubernetes,carlory/kubernetes,mahak/kubernetes,kubernetes/kubernetes,mosoft521/kubernetes,thockin/kubernetes,PiotrProkop/kubernetes,kubernetes/kubernetes,carlory/kubernetes,thockin/kubernetes,BenTheElder/kubernetes,MikeSpreitzer/kubernetes,mosoft521/kubernetes,warmchang/kubernetes,deads2k/kubernetes,jsafrane/kubernetes,warmchang/kubernetes,soltysh/kubernetes,GulajavaMinistudio/kubernetes,ping035627/kubernetes,dims/kubernetes,PiotrProkop/kubernetes,warmchang/kubernetes,dims/kubernetes,jessfraz/kubernetes,lojies/kubernetes,mkumatag/kubernetes,carlory/kubernetes,BenTheElder/kubernetes,BenTheElder/kubernetes,carlory/kubernetes,PiotrProkop/kubernetes,matthyx/kubernetes,lojies/kubernetes,mosoft521/kubernetes,liggitt/kubernetes,GulajavaMinistudio/kubernetes,kevin-wangzefeng/kubernetes,GulajavaMinistudio/kubernetes,dims/kubernetes,mkumatag/kubernetes,kevin-wangzefeng/kubernetes,thockin/kubernetes,jessfraz/kubernetes,jackfrancis/kubernetes,MikeSpreitzer/kubernetes,liggitt/kubernetes,mkumatag/kubernetes,kubernetes/kubernetes,ping035627/kubernetes,kevin-wangzefeng/kubernetes,deads2k/kubernetes,k82cn/kubernetes,mahak/kubernetes,enj/kubernetes,matthyx/kubernetes,jsafrane/kubernetes,dims/kubernetes,deads2k/kubernetes,olivierlemasle/kubernetes,enj/kubernetes,enj/kubernetes,mosoft521/kubernetes,mahak/kubernetes,lojies/kubernetes,jessfraz/kubernetes,enj/kubernetes,mkumatag/kubernetes,MikeSpreitzer/kubernetes,ping035627/kubernetes,matthyx/kubernetes,MikeSpreitzer/kubernetes,dims/kubernetes,kubernetes/kubernetes,olivierlemasle/kubernetes,thockin/kubernetes,enj/kubernetes,GulajavaMinistudio/kubernetes,jackfrancis/kubernetes,PiotrProkop/kubernetes,deads2k/kubernetes,liggitt/kubernetes,mahak/kubernetes