Add admonition for caveat on finding PSPs in use

Add a caution admonition for a caveat on using the kubectl get psp strategy to find which PSPs are still in use in the cluster.

docs/how-to-guides/new-user-guides/authentication-permissions-and-global-configuration/pod-security-standards.md

@@ -24,6 +24,10 @@ You must perform the following steps _while still in Kubernetes v1.24_:
 
 1. Map your active PSPs to Pod Security Standards:
     1. See which PSPs are still active in your cluster:
+       :::caution
+       This strategy might miss workloads that are not currently running, such as CronJobs, workloads that scale to zero, or workloads that have not rolled out yet.
+       :::
+       
        ```shell
        kubectl get pods \
          --all-namespaces \