Added update mention

Author: mnocon

docs/update_and_migration/from_4.6/update_from_4.6.md

@@ -372,6 +372,10 @@ Run the following scripts:
     psql <database_name> < vendor/ibexa/installer/upgrade/db/postgresql/ibexa-4.6.20-to-4.6.21.sql
     ```
 
+## v4.6.22
+
+No additional steps needed.
+
 [[% include 'snippets/update/notify_support.md' %]]
 
 With the product updated to the latest version, you can now finish the update process or proceed to updating the LTS Updates packages.