other: add better example in readme

README.md

@@ -49,10 +49,29 @@ roles:
     version: main
 ```
 
+#### Example using DNS challenge with designate provider
 ```yaml
 - hosts: all
-  roles:
-    - hdacloud.certbot
+  tasks:
+    - name: Obtain certificate
+      ansible.builtin.import_role:
+        name: hdacloud.certs
+      vars:
+        cert_fqdns:
+          - "{{ my_fqdn }}"
+        admin_email: "admin@example.org"
+        dns_challenge: true
+        lego_version: "4.11.0"
+        lego_dns_provider: "designate"
+        dns_provider_auth_env_variables:
+          OS_AUTH_URL: "https://h-da.cloud:13000"
+          OS_REGION_NAME: "eu-central"
+          OS_AUTH_TYP: "v3applicationcredential"
+          OS_APPLICATION_CREDENTIAL_ID: "{{ os_application_credential_id }}"
+          OS_APPLICATION_CREDENTIAL_SECRET: "{{ os_application_credential_secret }}"
+        renewal_hook: |
+          #!/usr/bin/env bash
+          systemctl restart httpd
 ```
 
 ### Info when using DNS challenge