Adding warning about auto defrag of etcd data causing harmless restart

Author: skrthomas

modules/etcd-defrag.adoc

@@ -29,6 +29,11 @@ Verify that the defragmentation process is successful by viewing one of these lo
 * cluster-etcd-operator pod
 * operator status error log
 
+[WARNING]
+====
+Automatic defragmentation can cause leader election failure in various OpenShift core components, such as the Kubernetes controller manager, which triggers a restart of the failing component. The restart is harmless and either triggers failover to the next running instance or the component resumes work again after the restart.
+====
+
 .Example log output
 [source,terminal]
 ----