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-present-with-managedby_host.yml

@@ -4,7 +4,7 @@
   become: true
 
   tasks:
-    ipahost:
+  - ipahost:
       ipaadmin_password: SomeADMINpassword
       hosts:
       - name: host01.exmaple.com