Add better explanation to change set

Author: aug24

.changeset/angry-parrots-confess.md

@@ -4,3 +4,13 @@
 
 Add a class for safe instantiation of managed policies with a specific structure of path
 which enables them to be discoverable.
+
+This enables teams to define sets of permissions which are re-usable and can be used to 
+create credentials suitable to approach a given workload, consistent with the Principle
+of Least Privilege.  This is preferred to existing workflows where a wide-ranging
+developer role is used.
+
+These can be reused in multiple locations, so, for example, an EC2 instance can be given
+a specific set of permissions which are also identically available for a support task.
+Changing one would then change the other, ensuring encapsulation of requirements in a 
+single place.