Add tutorial for audit policy

This tutorial was assembled from information provided in #4488.

site/content/en/docs/Tutorials/audit-policy.md

+---
+title: "Audit Policy"
+linkTitle: "Audit Policy"
+weight: 1
+date: 2019-11-19
+description: >
+  Enabling audit policy for minikube
+---
+
+## Overview
+
+[Auditing](https://kubernetes.io/docs/tasks/debug-application-cluster/audit/) is not enabled in minikube by default.
+This tutorial shows how to provide an [Audit Policy](https://kubernetes.io/docs/tasks/debug-application-cluster/audit/#audit-policy) file
+to the minikube API server on startup.
+
+## Tutorial
+
+```shell
+minikube stop
+
+mkdir -p ~/.minikube/files/etc/ssl/certs
+
+cat <<EOF > ~/.minikube/files/etc/ssl/certs/audit-policy.yaml
+# Log all requests at the Metadata level.
+apiVersion: audit.k8s.io/v1
+kind: Policy
+rules:
+- level: Metadata
+EOF
+
+minikube start \
+  --extra-config=apiserver.audit-policy-file=/etc/ssl/certs/audit-policy.yaml \
+  --extra-config=apiserver.audit-log-path=-
+
+kubectl logs kube-apiserver-minikube -n  kube-system | grep audit.k8s.io/v1
+```
+
+Putting the file into the `~/.minikube/files/` directory triggers the [file sync mechanism](https://minikube.sigs.k8s.io/docs/tasks/sync/) to copy the `audit-policy.yaml` file
+from the host onto the minikube node. When the API server container starts I'll mount the `/etc/ssl/certs` directory from the minikube node and can thus read the audit policy file. 
+
+You most likely want to tune the [Audit Policy](https://kubernetes.io/docs/tasks/debug-application-cluster/audit/#audit-policy) next as the one used in this tutorial is quite verbose.
+To use a new file you need to stop and start minikube.