old_contents: from django.contrib import admin
  
  from .models import Playbook
  
  admin.site.register(Playbook)
  
new_contents: from django.contrib import admin
  
  from .models import Playbook, Registry
  
  admin.site.register(Playbook)
  admin.site.register(Registry)
  
subject: Add Playbooks and Regitries in admin