Rewrite PodSecurityPolicy guide

Author: tallclair

docs/concepts/policy/psp.yaml renamed to docs/concepts/policy/example-psp.yaml

@@ -1,8 +1,10 @@
 apiVersion: extensions/v1beta1
 kind: PodSecurityPolicy
 metadata:
-  name: permissive
+  name: example
 spec:
+  privileged: false  # Don't allow privileged pods!
+  # The rest fills in some required fields.
   seLinux:
     rule: RunAsAny
   supplementalGroups:
@@ -11,10 +13,5 @@ spec:
     rule: RunAsAny
   fsGroup:
     rule: RunAsAny
-  hostPorts:
-  - min: 8000
-    max: 8080
   volumes:
   - '*'
-  allowedCapabilities:
-  - '*'