OSDOCS-3709: Adding Important block for FC storage on arm

Author: kelbrown20

storage/persistent_storage/persistent-storage-fibre.adoc

@@ -10,6 +10,11 @@ toc::[]
 {product-title} cluster with persistent storage using Fibre channel volumes.
 Some familiarity with Kubernetes and Fibre Channel is assumed.
 
+[IMPORTANT]
+====
+Persistent storage using Fibre Channel is not supported on ARM architecture based infrastructures.
+====
+
 The Kubernetes persistent volume framework allows administrators to provision a
 cluster with persistent storage and gives users a way to request those
 resources without having any knowledge of the underlying infrastructure.