Is this a BUG REPORT or FEATURE REQUEST?:

/kind bug

What happened:
Deprecated usage message is not getting printed , such as --container-port in kubectl export, --interactive in kubectl log, --experimental-use-openapi-print-columns in kubectl get.

Because cobra is used in kubectl, the issue is imported by cobra.
spf13/cobra#463
spf13/cobra#466

Should we update cobra in vendor?

$ kubectl expose --help
Expose a resource as a new Kubernetes service.
...
Options:
...
--container-port='': Synonym for --target-port

$ kubectl log --help
...
Options:
...
--interactive=false: If true, prompt the user for input when required.

What you expected to happen:
$ kubectl expose --help
Expose a resource as a new Kubernetes service.
...
Options:
...
--container-port='': --container-port will be removed in the future, please use --target-port instead

$ kubectl log --help
...
Options:
...
--interactive=false: This flag is no longer respected and there is no replacement.

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• Kubernetes version (use kubectl version):
  Client Version: version.Info{Major:"1", Minor:"8", GitVersion:"v1.8.2", GitCommit:"bdaeafa71f6c7c04636251031f93464384d54963", GitTreeState:"clean", BuildDate:"2017-10-24T19:48:57Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/amd64"}

• Cloud provider or hardware configuration:

• OS (e.g. from /etc/os-release):

• Kernel (e.g. uname -a):

• Install tools:

• Others: