Merge pull request #47732 from bergerhoffer/OSDOCS-3554

OSDOCS-3554: Updating migration content for 4.11

Author: bergerhoffer

migrating_from_ocp_3_to_4/planning-migration-3-4.adoc

@@ -122,6 +122,18 @@ If you used one of these in {product-title} 3.11, you must choose a different pe
 
 For more information, see xref:../storage/understanding-persistent-storage.adoc#understanding-persistent-storage[Understanding persistent storage].
 
+[discrete]
+==== Migration of in-tree volumes to CSI drivers
+
+{product-title} 4 is migrating in-tree volume plug-ins to their Container Storage Interface (CSI) counterparts. In {product-title} {product-version}, CSI drivers are the new default for the following in-tree volume types:
+
+* Azure Disk
+* OpenStack Cinder
+
+All aspects of volume lifecycle, such as creation, deletion, mounting, and unmounting, is handled by the CSI driver.
+
+For more information, see xref:../storage/container_storage_interface/persistent-storage-csi-migration.adoc#persistent-storage-csi-migration[CSI automatic migration].
+
 [id="migration-preparing-networking"]
 === Networking considerations