Update how-to-upgrade-cluster.md

Added images

Author: suvishodcitus

articles/cosmos-db/mongodb/vcore/how-to-upgrade-cluster.md

@@ -34,12 +34,14 @@ Here are the detailed steps to upgrade a cluster to latest version:
 
 2. Go to the **Overview** blade of your Azure Cosmos DB for MongoDB vCore cluster and click the **Upgrade** button as illustrated below.
 
+:::image type="content" source="media/how-to-scale-cluster/upgrade-overview-page.png" alt-text="Screenshot of the overview page.":::
+
 > [!NOTE]
 > The upgrade button will stay disabled if you're already using the latest version.
 
 3. A new window will appear on the right, allowing you to choose the MongoDB version you wish to upgrade to. Select the appropriate version and submit the upgrade request.
 
-
+:::image type="content" source="media/how-to-scale-cluster/upgrade-side-window.png" alt-text="Screenshot of server upgrade page.":::
 
 ## Next steps