add docstring for ProductType.

apps/product/views/back.py

@@ -111,13 +111,47 @@ class ProductListCreateBackOfficeView(ProductBackOfficeMixinView,
 
 class ProductTypeListCreateBackOfficeView(ProductTypeBackOfficeMixinView,
                                           generics.ListCreateAPIView):
-    """Product type back-office list-create view."""
+    """
+    Product type back-office list-create view.
+
+    **GET**
+    ```
+    Implement getting ProductType list.
+    ```
+
+    **POST**
+    ```
+    Implement creating ProductType.
+    ```
+    """
     serializer_class = serializers.ProductTypeBackOfficeDetailSerializer
 
 
 class ProductTypeRUDBackOfficeView(ProductTypeBackOfficeMixinView,
                                    generics.RetrieveUpdateDestroyAPIView):
-    """Product type back-office retrieve-update-destroy view."""
+    """
+    Product type back-office retrieve-update-destroy view.
+
+    **GET**
+    ```
+    Implement getting ProductType object.
+    ```
+
+    **PUT**
+    ```
+    Implement updating ProductType.
+    ```
+
+    **PATCH**
+    ```
+    Implement partial updating ProductType.
+    ```
+
+    **DELETE**
+    ```
+    Implement deleting ProductType.
+    ```
+    """
     serializer_class = serializers.ProductTypeBackOfficeDetailSerializer