Automatic merge from submit-queue (batch tested with PRs 37608, 37103, 37320, 37607, 37678)
add some help info about the 'all' arg
**What this PR does / why we need it**:
There is an arg named "all" in the get command, we can use it like "kubectl get all". But we can get nothing about this arg in the help description. Users may not know how to use it without looking into the source code. So here I'm going to add some description about this arg.
**Which issue this PR fixes**
We discussed about this in
In pkg/kubectl/cmd/get.go there is a confused arg named "all" [#37533](https://github.com/kubernetes/kubernetes/issues/37533)
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