Update constraint label topic (#130)

* Update constraint label topic

* Incorporate feedback

datacenter/ucp/2.2/guides/admin/configure/add-labels-to-cluster-nodes.md

@@ -31,14 +31,12 @@ details pane, click **Configure**.
 
 In the **Edit Node** page, scroll down to the **Labels** section.
 
-Click **Add Label**, and add a label that has a key set to `nodel.labels.disk`
-and a value of `ssd`. 
+Click **Add Label**, and add a label with the key `disk` and a value of `ssd`. 
 
 ![](../../images/add-labels-to-cluster-nodes-2.png){: .with-border}
 
-When you're done, click **Save** and dismiss the **Edit Node** page.
-In the node's details pane, click **Labels** to view the labels that are
-applied to the node. 
+Click **Save** and dismiss the **Edit Node** page. In the node's details
+pane, click **Labels** to view the labels that are applied to the node. 
 
 You can also do this from the CLI by running:
 
@@ -46,20 +44,85 @@ You can also do this from the CLI by running:
 $ docker node update --label-add <key>=<value> <node-id>
 ```
 
-## Add a constraint to a service
+## Deploy a service with constraints
 
 When deploying a service, you can specify constraints, so that the service gets
 scheduled only on a node that has a label that fulfills all of the constraints
 you specify.
 
-In this example, when users deploy a service, they can add constraints for the
-service to be scheduled on nodes that have SSD storage.
+In this example, when users deploy a service, they can add a constraint for the
+service to be scheduled only on nodes that have SSD storage.
 
-You can add deployment constraints to your docker-stack.yml file or when you're
-creating a stack:
-![](../../images/use-contraints-in-stack-deployement.png)
+Navigate to the **Stacks** page. Name the new stack "wordpress", and in the
+**Mode** dropdown, check **Services**.
+
+In the **Compose.yml** editor, paste the following stack file.
+
+```
+version: "3.1"
+
+services:
+  db:
+    image: mysql:5.7
+    deploy:
+      placement:
+        constraints:
+          - node.labels.disk == ssd
+      restart_policy:
+        condition: on-failure
+    networks:
+      - wordpress-net
+    environment:
+      MYSQL_ROOT_PASSWORD: wordpress
+      MYSQL_DATABASE: wordpress
+      MYSQL_USER: wordpress
+      MYSQL_PASSWORD: wordpress
+  wordpress:
+    depends_on:
+      - db
+    image: wordpress:latest
+    deploy:
+      replicas: 1
+      placement:
+        constraints:
+          - node.labels.disk == ssd
+      restart_policy:
+        condition: on-failure
+        max_attempts: 3
+    networks:
+      - wordpress-net
+    ports:
+      - "8000:80"
+    environment:
+      WORDPRESS_DB_HOST: db:3306
+      WORDPRESS_DB_PASSWORD: wordpress
+
+networks:
+  wordpress-net:
+```
+
+Click **Create** to deploy the stack, and when the stack deploys,
+click **Done**.
+
+![](../../images/use-constraints-in-stack-deployment.png)
+
+Navigate to the **Nodes** page, and click the node that has the
+`disk` label. In the details pane, click the **Inspect Resource**
+dropdown and select **Containers**.  
+
+![](../../images/use-constraints-in-stack-deployment-2.png)
+
+Dismiss the filter and navigate to the **Nodes** page. Click a node that
+doesn't have the `disk` label. In the details pane, click the
+**Inspect Resource** dropdown and select **Containers**. There are no 
+WordPress containers scheduled on the node. Dismiss the filter.
+
+## Add a constraint to a service by using the UCP web UI
+
+You can declare the deployment constraints in your docker-stack.yml file or
+when you're creating a stack. Also, you can apply them when you're creating
+a service.
 
-Or you can apply them when you're creating a service.
 To check if a service has deployment constraints, navigate to the 
 **Services** page and choose the service that you want to check.
 In the details pane, click **Constraints** to list the constraint labels.
@@ -69,7 +132,7 @@ To edit the labels on the service, click **Configure** and select
 
 ![](../../images/add-constraint-to-service.png)
 
-From here, you can add or remove deployment constraints, too.
+You can add or remove deployment constraints on this page.
 
 ## Where to go next