Add example cert.yaml and fix Ingress

kube/untested/cert.yaml

+apiVersion: certmanager.k8s.io/v1alpha1
+kind: Certificate
+metadata:
+  name: webserver-cheerp-cert
+  namespace: default
+spec:
+  secretName: webserver-cheerp-tls
+  issuerRef:
+    name: letsencrypt-staging
+  commonName: cheerp.cppse.nl
+  dnsNames:
+  - cheerp.cppse.nl
+  acme:
+    config:
+    - http01:
+        ingressClass: nginx
+      domains:
+      - cheerp.cppse.nl
+    - http01:
+        ingress: my-ingress
+      domains:
+      - cheerp.cppse.nl
+

kube/ingress.yaml → kube/untested/ingress.yaml

   annotations:
     # enable kube-lego for this ingress
     kubernetes.io/tls-acme: "true"
+    nginx.ingress.kubernetes.io/rewrite-target: /
 spec:
   # this enables tls for the specified domain names
   tls: