mention service account configuration in examples

examples/README.md

@@ -0,0 +1,13 @@
+## Examples
+
+Since you need to provide service account for App CRs, we've included two common service account configurations:
+
+- https://github.com/k14s/kapp-controller/blob/master/examples/rbac/default-ns.yml: It creates `default-ns-sa` service account in `default` namespace that allows to change any resource in `default` namespace. (Example usage: `simple-app-http.yml`)
+
+- https://github.com/k14s/kapp-controller/blob/master/examples/rbac/cluster-admin.yml: It creates `cluster-admin-sa` service account within `default` namespace that allows to change _any_ resource in the cluster. (Example usage: `istio-knative.yml`)
+
+```bash
+$ kapp deploy -a default-ns-rbac -f https://github.com/k14s/kapp-controller/blob/master/examples/rbac/default-ns.yml
+```
+
+Once that's done, deploy any example in this repo.