Documentation: fix typo s/endpoint-health/endpoint health/

Documentation/op-guide/container.md

@@ -57,7 +57,7 @@ sudo rkt run --net=default:IP=${NODE3} coreos.com/etcd:v3.0.6 -- -name=node3 -ad
 Verify the cluster is healthy and can be reached.
 
 ```
-ETCDCTL_API=3 etcdctl --endpoints=http://172.16.28.21:2379,http://172.16.28.22:2379,http://172.16.28.23:2379 endpoint-health
+ETCDCTL_API=3 etcdctl --endpoints=http://172.16.28.21:2379,http://172.16.28.22:2379,http://172.16.28.23:2379 endpoint health
 ```
 
 ### DNS