Fix ansible-lint error 502 (unnamed-task) for example playbooks.

This patch adds 'name' to all example playbook tasks that did not
have it, fixing ansible-lint's error 'unnamed-task'.

playbooks/service/service-is-absent.yml

@@ -5,8 +5,8 @@
   gather_facts: false
 
   tasks:
-  # Ensure service is absent
-  - ipaservice:
+  - name: Ensure service is absent
+    ipaservice:
       ipaadmin_password: SomeADMINpassword
       name: HTTP/www.example.com
       state: absent