PodSecurityPolicy example: fix explanation

examples/podsecuritypolicy/rbac/README.md

@@ -82,21 +82,25 @@ podsecuritypolicy "restricted" created
 
 ### Roles and bindings
 
-In order to a `PodSecurityPolicy` a user must have the ability to perform the `use` verb on the policy.
-The `use` verb is a special verb that grants access to use the policy while
-not allowing any other access.  This verb is specific to `PodSecurityPolicy`.
-To enable the `use` access we will create cluster roles.  In this example we will provide the roles:
+In order to create a pod, either the creating user or the service account
+specified by the pod must be authorized to use a `PodSecurityPolicy` object
+that allows the pod. That authorization is determined by the ability to perform
+the `use` verb on a particular `podsecuritypolicies` resource. The `use` verb
+is a special verb that grants access to use a policy while not permitting any
+other access. For this example, we'll first create RBAC `ClusterRoles` that
+enable access to `use` specific policies.
 
 1. `restricted-psp-user`: this role allows the `use` verb on the `restricted` policy only
 2. `privileged-psp-user`: this role allows the `use` verb on the `privileged` policy only
 
 
-To associate roles with users we will use groups via a `RoleBinding`.  This example uses
-the following groups:
+We can then create `ClusterRoleBindings` to grant groups of users the
+"restricted" and/or "privileged" `ClusterRoles`.  In this example, the bindings
+grant the following roles to groups.
 
 1. `privileged`: this group is bound to the `privilegedPSP` role and `restrictedPSP` role which gives users
 in this group access to both policies.
-1. `restricted`: this group is bound to the `restrictedPSP` role
+1. `restricted`: this group is bound to the `restrictedPSP` role.
 1. `system:authenticated`: this is a system group for any authenticated user.  It is bound to the `edit`
 role which is already provided by the cluster.