add example to import a playbook from collection (#78443)

lib/ansible/modules/import_playbook.py

@@ -59,6 +59,9 @@ EXAMPLES = r'''
   vars:
     service: httpd
 
+- name: Include a playbook from a collection
+  ansible.builtin.import_playbook: my_namespace.my_collection.my_playbook
+
 - name: This DOES NOT WORK
   hosts: all
   tasks: