added url endpoint for authorcreate view in urls.py in bookshelf module

bookshelf/urls.py

-from django.urls import path
+from django.urls import path, re_path
 from .views import HomePageView, BookListView, BookDetailView, BookCreateView,\
-    AuthorListView, AuthorDetailView
+    AuthorListView, AuthorCreateView, AuthorDetailView
 
 urlpatterns = [
     path('homepage/', HomePageView.as_view()),
     path('books/', BookListView.as_view()),
     path('books/add/', BookCreateView.as_view()),
-    path('books/<int:pk>/details/', BookDetailView.as_view()),
+    path('books/<int:pk>/details/', BookDetailView.as_view(), name='bookdetailview'),
     path('authors/', AuthorListView.as_view()),
-    path('authors/<int:pk>/details/', AuthorDetailView.as_view()),
+    path('authors/add/', AuthorCreateView.as_view()),
+    path('authors/<int:pk>/details/', AuthorDetailView.as_view(), name='authordetailview'),
 ]
+
+app_name = 'bookshelf'
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