cert-manager: add cert-manager for automatic certificate renewal

Add cert-manager with DNS-01 challenge support:
- Cloudflare (vhaudiquet.fr, buildpath.win)

kubernetes/system/cert-manager/kustomization.yaml

@@ -0,0 +1,16 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+namespace: cert-manager
+resources:
+  - namespace.yaml
+  - repository.yaml
+  - release.yaml
+  - cloudflare-api-token-secret.yaml
+  - ovh-api-credentials-secret.yaml
+  - clusterissuer.yaml
+secretGenerator:
+  - name: cert-manager-values
+    files:
+      - values.yaml=values.yaml
+configurations:
+  - kustomizeconfig.yaml