Update wording/header for volume expansion failure.

Co-authored-by: David Kilfoyle <[email protected]>

Author: naemono

troubleshoot/deployments/cloud-on-k8s/common-problems.md

@@ -308,7 +308,7 @@ GET /_security/role_mapping/<roleName>
 ```
 
 
-## If a volume expansion failed [k8s-common-problems-volume-failed-expansion]
+## Volume expansion failed [k8s-common-problems-volume-failed-expansion]
 
 If you attempted an expansion of an {{es}} data volume via its [volume claim template](/deploy-manage/deploy/cloud-on-k8s/volume-claim-templates.md#k8s-volume-claim-templates-update), you may have encountered scenarios where the operation failed. For example older versions of the Azure Disk CSI driver did not allow volume expansion without shutting down the Virtual Machine to which the volume was attached. If you try to adjust the volume claim template back to the original size you will encounter an error: