old_contents: 
  from django.contrib import admin
  from .models import Link
  
  
  admin.site.register(Link)
  
new_contents: 
  from django.contrib import admin
  from mezzanine.core.admin import DisplayableAdmin
  from .models import Link
  
  
  admin.site.register(Link, DisplayableAdmin)
  
subject: Use DisplayableAdmin for links