Replace link to zookeeper.yaml

The link in the sample command "kubectl apply" pointed to a YAML file that was rendered wrongly. I replaced the problem link to a link to the same file on git, which avoids the rendering issue.

docs/tutorials/stateful-application/zookeeper.md

@@ -100,7 +100,7 @@ Open a command terminal, and use
 manifest.
 
 ```shell
-kubectl apply -f https://k8s.io/docs/tutorials/stateful-application/zookeeper.yaml
+kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/docs/tutorials/stateful-application/zookeeper.yaml
 ```
 
 This creates the `zk-hs` Headless Service, the `zk-cs` Service,