Fix indentation issues

content/en/docs/tutorials/stateful-application/cassandra.md

@@ -183,6 +183,7 @@ Use `kubectl edit` to modify the size of a Cassandra StatefulSet.
     **Note:** The following sample is an excerpt of the StatefulSet file.
     {{< /note >}}
 
+    ```yaml
     # Please edit the object below. Lines beginning with a '#' will be ignored,
     # and an empty file will abort the edit. If an error occurs while saving this file will be
     # reopened with the relevant failures.
@@ -201,6 +202,7 @@ Use `kubectl edit` to modify the size of a Cassandra StatefulSet.
       uid: 7a219483-6185-11e6-a910-42010a8a0fc0
     spec:
       replicas: 3
+    ```
 
 2. Change the number of replicas to 4, and then save the manifest. 
 
@@ -253,4 +255,3 @@ Deleting or scaling a StatefulSet down does not delete the volumes associated wi
 
 {{% /capture %}}
 
-