Improve README.md

staging/cert-manager-setup/README.md

@@ -1,13 +1,23 @@
 # cert-manager-setup
 
 cert-manager-setup installs [cert-manager](https://github.com/jetstack/cert-manager/blob/master/deploy/charts/cert-manager/README.md) which is a Kubernetes addon to automate the management and issuance of
-TLS certificates from various issuing sources
+TLS certificates from various issuing sources.
 
-It will ensure certificates are valid and up to date periodically, and attempt
+`cert-manager` will ensure certificates are valid and up to date periodically, and attempt
 to renew certificates at an appropriate time before expiry.
 
-In addition to installing cert-manager, cert-manager-setup provides the capability to specify `ClusterIssuers` in the `values.yaml` file which will be applied directly after the `cert-manager` installation has completed.
+In addition to installing `cert-manager`, `cert-manager-setup` provides the capability to specify a `ClusterIssuer` in the `values.yaml` file which will be applied directly after the `cert-manager` installation has completed.
 
-# notes
+# Supported values format
 
-In order to submit the `ClusterIssuers` post installation, `cert-manager-setup` runs a post-install `Job` hook. In case that the hook fails the Job will not be cleaned up by Helm. This behavior is intended to ease debugging.
+```yaml
+clusterissuer:
+  name: clusterissuer-name
+  spec:
+    ca:
+      secretName: clusterissuer-secret
+```
+
+# Notes
+
+In order to submit the `ClusterIssuer` post installation, `cert-manager-setup` runs a post-install `Job` hook. In case that the hook fails the Job will not be cleaned up by Helm. This behavior is intended to ease debugging.