Merge pull request etcd-io#10850 from Koprvhdix/role-remove-document-fix

Documentation: change `etcdctl role remove` to `etcdctl role delete`

Documentation/op-guide/authentication.md

@@ -119,7 +119,7 @@ $ etcdctl role revoke-permission myrolename /foo/bar
 As is removing a role entirely:
 
 ```
-$ etcdctl role remove myrolename
+$ etcdctl role delete myrolename
 ```
 
 ## Enabling authentication