Update deploy-bare-metal.md (#694)

add explain for using multiple zk server in bookie metadataServiceUri setting

docs/deploy-bare-metal.md

@@ -302,6 +302,18 @@ You can configure BookKeeper bookies using the [`conf/bookkeeper.conf`](referenc
 metadataServiceUri=zk://zk1.us-west.example.com:2181/ledgers
 ```
 
+:::note
+
+If you want to use multiple ZooKeeper servers, you can use as follow format:
+
+```properties
+metadataServiceUri=zk://zk1.us-west.example.com:2181;zk2.us-west.example.com:2181;zk3.us-west.example.com:2181/ledgers
+```
+
+Which using `;` as separator in `metadataServiceUri`
+
+:::
+
 Once you appropriately modify the `metadataServiceUri` parameter, you can make any other configuration changes that you require. You can find a full listing of the available BookKeeper configuration parameters [here](reference-configuration.md#bookkeeper). However, consulting the [BookKeeper documentation](https://bookkeeper.apache.org/docs/next/reference/config/) for a more in-depth guide might be a better choice.
 
 Once you apply the desired configuration in `conf/bookkeeper.conf`, you can start up a bookie on each of your BookKeeper hosts. You can start up each bookie either in the background, using [nohup](https://en.wikipedia.org/wiki/Nohup), or in the foreground.