Document OSP PV limit workaround

Commit implements https://issues.redhat.com/browse/OSDOCS-1278

Author: maxwelldb

modules/installation-configuration-parameters.adoc

@@ -457,6 +457,14 @@ You must set this parameter to perform an installation in a restricted network.
 For example, `\http://mirror.example.com/images/rhcos-43.81.201912131630.0-openstack.x86_64.qcow2.gz?sha256=ffebbd68e8a1f2a245ca19522c16c86f67f9ac8e4e0c1f0a812b068b16f7265d`.
 The value can also be the name of an existing Glance image, for example `my-rhcos`.
 
+|`platform.openstack.clusterOSImageProperties`
+|Properties to add to the installer-uploaded ClusterOSImage in Glance. This property is ignored if `platform.openstack.clusterOSImage` is set to an existing Glance image.
+
+You can use this property to exceed the default persistent volume (PV) limit for {rh-openstack} of 26 PVs per node. To exceed the limit, set the `hw_scsi_model` property value to `virtio-scsi` and the `hw_disk_bus` value to  `scsi`.
+
+You can also use this property to enable the QEMU guest agent by including the `hw_qemu_guest_agent` property with a value of `yes`.
+|A list of key-value string pairs. For example, `["hw_scsi_model": "virtio-scsi", "hw_disk_bus": "scsi"]`.
+
 |`platform.openstack.defaultMachinePlatform`
 |The default machine pool platform configuration.
 |