Fix host's module managedby_host playbooks.

The host's module example playbooks had syntax errors that prevented
its execution. The tasks were described as dicts rather than lists.

playbooks/host/hosts-member-managedby_host-present.yml

@@ -4,6 +4,7 @@
   become: true
 
   tasks:
+  - name: Ensure hosts manadegby_host is absent.
     ipahost:
       ipaadmin_password: SomeADMINpassword
       hosts: