suggest use of kube explain <resource> in kube get output

This patch improves usability flow, making it easier for a user to
discover the command `kube explain <resource>` through `kube get`
output.

pkg/kubectl/cmd/cmd.go

@@ -287,7 +287,7 @@ Find more information at https://github.com/kubernetes/kubernetes.`,
 				NewCmdDescribe(f, out, err),
 				NewCmdLogs(f, out),
 				NewCmdAttach(f, in, out, err),
-				NewCmdExec("kubectl", f, in, out, err),
+				NewCmdExec(cmds.Root().CommandPath(), f, in, out, err),
 				NewCmdPortForward(f, out, err),
 				NewCmdProxy(f, out),
 			},