Updates url to point to the glossary

Substitutes the existing url to archived documentation of "Kubernetes Resource" with URL pointing to glossary .

Fixes the #31396

Author: amej

content/en/docs/concepts/storage/persistent-volumes.md

@@ -422,7 +422,7 @@ Helper programs relating to the volume type may be required for consumption of a
 
 ### Capacity
 
-Generally, a PV will have a specific storage capacity.  This is set using the PV's `capacity` attribute.  See the Kubernetes [Resource Model](https://git.k8s.io/community/contributors/design-proposals/scheduling/resources.md) to understand the units expected by `capacity`.
+Generally, a PV will have a specific storage capacity.  This is set using the PV's `capacity` attribute.  Read the glossary term [Quantity](https://kubernetes.io/docs/reference/glossary/?all=true#term-quantity) to understand the units expected by `capacity`.
 
 Currently, storage size is the only resource that can be set or requested.  Future attributes may include IOPS, throughput, etc.