Adds postgresql data migration procedure (#755)

Co-authored-by: Steven Smith <stevsmit@stevsmit.remote.csb>

modules/proc_upgrade_standalone.adoc

@@ -24,9 +24,9 @@ In some cases, {productname} supports direct, single-step upgrades from prior (N
 //link
 For users wanting to upgrade the {productname} Operator, see link:https://access.redhat.com/documentation/en-us/red_hat_quay/{producty}/html-single/upgrade_red_hat_quay/index#upgrading_quay_by_upgrading_the_quay_operator[Upgrading the {productname} Operator Overview].
 
-This document describess the steps needed to perform each individual upgrade. Determine your current version and then follow the steps in sequential order, starting with your current version and working up to your desired target version.
+This document describes the steps needed to perform each individual upgrade. Determine your current version and then follow the steps in sequential order, starting with your current version and working up to your desired target version.
 
-*link:https://access.redhat.com/documentation/en-us/red_hat_quay/{producty}/html-single/upgrade_red_hat_quay/index#upgrade_to_3_9_z_from_3_8_z[Upgrade to 3.9.z from 3.8.z]
+* link:https://access.redhat.com/documentation/en-us/red_hat_quay/{producty}/html-single/upgrade_red_hat_quay/index#upgrade_to_3_9_z_from_3_8_z[Upgrade to 3.9.z from 3.8.z]
 *link:https://access.redhat.com/documentation/en-us/red_hat_quay/{producty}/html-single/upgrade_red_hat_quay/index#upgrade_to_3_9_z_from_3_7_z[Upgrade to 3.9.z from 3.7.z]
 * link:https://access.redhat.com/documentation/en-us/red_hat_quay/{producty}/html-single/upgrade_red_hat_quay/index#upgrade_to_3_8_z_from_3_7_z[Upgrade to 3.8.z from 3.7.z]
 * link:https://access.redhat.com/documentation/en-us/red_hat_quay/{producty}/html-single/upgrade_red_hat_quay/index#upgrade_to_3_7_z_from_3_6_z[Upgrade to 3.7.z from 3.6.z]
@@ -54,7 +54,6 @@ The general procedure for a manual upgrade consists of the following steps:
 . Start Clair using the new version of the image.
 . Wait until Clair is ready to accept connections before starting the new version of Quay.
 
-
 == Accessing images
 
 Images for Quay 3.4.0 and later are available from link:https://registry.redhat.io[registry.redhat.io] and
@@ -64,6 +63,19 @@ Images for Quay 3.3.4 and earlier are available from link:https://quay.io[quay.i
 
 == Upgrade to 3.9.z from 3.8.z
 
+If you are upgrading your standalone {productname} deployment from 3.8.z -> 3.9, it is highly recommended that you upgrade PostgreSQL from version 10 -> 13. To upgrade PostgreSQL from 10 -> 13, you must bring down your PostgreSQL 10 database and run a migration script to initiate the process:
+
+[source,terminal]
+----
+$ podman run -d --name postgresql_database \
+    -e POSTGRESQL_MIGRATION_REMOTE_HOST=172.17.0.2 \
+    -e POSTGRESQL_MIGRATION_ADMIN_PASSWORD=remoteAdminP@ssword \
+    [ OPTIONAL_CONFIGURATION_VARIABLES ]
+    rhel8/postgresql-13
+----
+
+For more information, see link:https://github.com/sclorg/postgresql-container/tree/master/13#data-migration[Data Migration].
+
 === Target images
 * **Quay:** {productrepo}/{quayimage}:{productminv}
 ifdef::downstream[]