deploy clusters on multiple servers (#856)

* updates

* Update deploy-nebula-graph-cluster.md

docs-2.0/4.deployment-and-installation/2.compile-and-install-nebula-graph/deploy-nebula-graph-cluster.md

@@ -1,6 +1,6 @@
-# Deploy Nebula Graph cluster with RPM/DEB package
+# Deploy Nebula Graph cluster with RPM/DEB package on multiple servers 
 
-For now, Nebula Graph does not provide an official deployment tool. Users can deploy a Nebula Graph cluster with RPM or DEB package manually. This topic provides some examples of deploying Nebula Graph clusters.
+For now, Nebula Graph does not provide an official deployment tool. Users can deploy a Nebula Graph cluster with RPM or DEB package manually. This topic provides an example of deploying a Nebula Graph cluster on multiple servers (machines).
 
 ## Deployment
 
@@ -256,7 +256,7 @@ Users can refer to the content of the following configurations, which only show
 
 ### Step 3: Start the cluster
 
-Start the corresponding service on each machine. Descriptions are as follows.
+Start the corresponding service on **each machine**. Descriptions are as follows.
 
 | Machine name | The process to be started |
 | :-----       | :---------------          |
@@ -274,6 +274,8 @@ sudo /usr/local/nebula/scripts/nebula.service start <metad|graphd|storaged|all>
 
 !!! note
 
+    - Make sure all the processes of services on each machine are started. Otherwise, you will fail to start Nebula Graph.
+
     - When the graphd process, the storaged process, and the metad process are all started, you can use `all` instead.
 
     - `/usr/local/nebula` is the default installation path for Nebula Graph. Use the actual path if you have customized the path. For more information about how to start and stop the services, see [Manage Nebula Graph services](../manage-service.md).

mkdocs.yml

@@ -292,7 +292,7 @@ nav:
           - Install Nebula Graph by compiling the source code: 4.deployment-and-installation/2.compile-and-install-nebula-graph/1.install-nebula-graph-by-compiling-the-source-code.md
           - Install Nebula Graph with RPM or DEB package: 4.deployment-and-installation/2.compile-and-install-nebula-graph/2.install-nebula-graph-by-rpm-or-deb.md
           - Deploy Nebula Graph with Docker Compose: 4.deployment-and-installation/2.compile-and-install-nebula-graph/3.deploy-nebula-graph-with-docker-compose.md
-          - Deploy Nebula Graph cluster: 4.deployment-and-installation/2.compile-and-install-nebula-graph/deploy-nebula-graph-cluster.md
+          - Deploy a Nebula Graph cluster on multiple servers: 4.deployment-and-installation/2.compile-and-install-nebula-graph/deploy-nebula-graph-cluster.md
       - Manage Service: 4.deployment-and-installation/manage-service.md
       - Connect to Service: 4.deployment-and-installation/connect-to-nebula-graph.md
       - Upgrade: