add doc for --as-group in cli

Add doc for this pr: kubernetes/kubernetes#43696
kubernetes · Sep 22, 2017 · 37613f2 · 37613f2
1 parent e9d9fee
commit 37613f2
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/docs/admin/authentication.md b/docs/admin/authentication.md
@@ -614,13 +614,13 @@ Impersonate-Extra-scopes: development
 ```
 
 When using `kubectl` set the `--as` flag to configure the `Impersonate-User`
-header.
+header, set the `--as-group` flag to configure the `Impersonate-Group` header.
 
 ```shell
 $ kubectl drain mynode
 Error from server (Forbidden): User "clark" cannot get nodes at the cluster scope. (get nodes mynode)
 
-$ kubectl drain mynode --as=superman
+$ kubectl drain mynode --as=superman --as-group=system:masters
 node "mynode" cordoned
 node "mynode" drained
 ```