old_contents: from django.conf.urls import url
  
  from ..views import CategoryList
  
  urlpatterns = [
      url(r'^$', CategoryList.as_view(), name='category-list'),
  ]
  
new_contents: from django.conf.urls import url
  
  from ..views import CategoryList, CategoryDetail
  
  urlpatterns = [
      url(r'^$', CategoryList.as_view(), name='category-list'),
      url(r'^(?P<slug>[\w-]+)$', CategoryDetail.as_view(), name='category-detail'),
  ]
  
subject: add category content url config