Recently, I got an inquiry from our customer. They asked us what is the maximum value for each limit.
From the upstream kesytone document, the unified quota set the value range between
-1 to 2147483647 (integer).

ref. https://docs.openstack.org/keystone/latest/admin/unified-limits.html

This information is useful for users who want to use the feature and will reduce the workload for support side.
Please add an acceptable value range for limits into our doc.

The target section will be:
https://docs.redhat.com/en/documentation/red_hat_openstack_services_on_openshift/18.0/html-single/customizing_persistent_storage/index#con_project-quota-types-and-limits_glance-quotas