docs: update README with a complete example

Signed-off-by: Doug Goldstein <[email protected]>

README.md

@@ -3,7 +3,93 @@
 A [cert-manager][cert-manager] webhook based [dns01 solver][webhook-solver]
 supporting [Rackspace Cloud DNS][raxclouddns].
 
-Please see the `examples/` directory for how to use this.
+## Installation
+
+### cert-manager
+
+This package is an addon to [cert-manager][cert-manager] so to get started you
+must first have installed it. Instructions can be found [here](https://cert-manager.io/docs/installation/)
+for installing it.
+
+### webhook
+
+The webhook must be installed in the same namespace that you've installed cert-manager.
+This next step assumes it was `cert-manager`.
+
+```bash
+helm install --namespace cert-manager cert-manager-webhook-rackspace charts/cert-manager-webhook-rackspace
+```
+
+To uninstall you can run the following:
+
+```bash
+helm uninstall --namespace cert-manager cert-manager-webhook-rackspace
+```
+
+## Usage
+
+To use the Rackspace Cloud DNS webhook, you must have an account with admin permissions
+to the Cloud DNS service and must know the Rackspace API key for that account.
+
+An example secret to provide the credentials would be:
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: rackspace-creds
+type: Opaque
+stringData:
+  username: my-username-here
+  api-key: my-api-key-here
+```
+
+Then you can create an `Issuer` or a `ClusterIssuer`. An example would be:
+
+```yaml
+apiVersion: cert-manager.io/v1
+kind: Issuer
+metadata:
+  name: letsencrypt-staging
+  namespace: cm-test
+spec:
+  acme:
+    # The ACME server URL
+    server: https://acme-staging-v02.api.letsencrypt.org/directory
+
+    # Email address used for ACME registration
+    email: [email protected] # REPLACE THIS WITH YOUR EMAIL!!!
+
+    # Name of a secret used to store the ACME account private key
+    privateKeySecretRef:
+      name: letsencrypt-staging
+
+    solvers:
+    - dns01:
+        webhook:
+          groupName: acme.mycompany.com  # replace with the groupName you set for the helm chart
+          solverName: rackspace
+          config:
+            authSecretRef: rackspace-creds
+            domainName: some.domain.tld
+```
+
+You can then create a certificate like:
+
+```yaml
+apiVersion: cert-manager.io/v1
+kind: Certificate
+metadata:
+  name: example-cert
+spec:
+  commonName: something.some.domain.tld
+  dnsNames:
+    - something.some.domain.tld
+  issuerRef:
+    name: letsencrypt-staging
+    kind: Issuer
+  secretName: example-cert
+```
 
 [cert-manager]: <https://cert-manager.io>
 [webhook-solver]: <https://cert-manager.io/docs/configuration/acme/dns01/webhook/>

examples/rackspace-issuer.yaml

@@ -17,7 +17,7 @@ spec:
     solvers:
     - dns01:
         webhook:
-          groupName: com.yourdomain.acme
+          groupName: acme.mycompany.com
           solverName: rackspace
           config:
             authSecretRef: rackspace-creds