Add information about Parallel Pod Management

Clarify information that Parallel Pod Management works only during scaling.

Author: es1o

content/en/docs/tutorials/stateful-application/basic-stateful-set.md

@@ -1083,7 +1083,7 @@ above.
 `Parallel` pod management tells the StatefulSet controller to launch or
 terminate all Pods in parallel, and not to wait for Pods to become Running
 and Ready or completely terminated prior to launching or terminating another
-Pod.
+Pod. This option only affects the behavior for scaling operations. Updates are not affected.
 
 {{< codenew file="application/web/web-parallel.yaml" >}}