Add support for psp

docs/examples/psp/README.md

@@ -0,0 +1,23 @@
+# Pod Security Policy (PSP)
+
+In most clusters today, by default, all resources (e.g. Deployments and ReplicatSets)
+have permissions to create pods.
+Kubernetes however provides a more fine-grained authorization policy called 
+[Pod Security Policy (PSP)](https://kubernetes.io/docs/concepts/policy/pod-security-policy/).
+
+PSP allows the cluster owner to define the permission of each object, for example creating a pod.
+If you have PSP enabled on the cluster, and you deploy ingress-nginx,
+you will need to provide the Deployment with the permissions to create pods.
+
+Before applying any objects, first apply the PSP permissions by running:
+```console
+kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/docs/examples/psp/psp.yaml
+```
+
+Now that the pod security policy is applied, we can continue as usual by applying the
+[mandatory.yaml](../../../deploy/static/mandatory.yaml)
+according to the [Installation Guide](../../deploy/index.md). 
+
+Note: PSP permissions must be granted before to the creation of the Deployment and the ReplicaSet.
+If the Deployment or ReplicaSet already exist, they will receive the PSP permissions
+only after deleting them and reapplying mandatory.yaml.