Add helper comments for empty files

apps/core/constants.py

@@ -0,0 +1 @@
+# Add your app constants here.

apps/core/exceptions.py

@@ -3,4 +3,4 @@
     who consumes your APIs. To learn how to create a custom exception handler,
     you can check out the Django Rest Framework documentation at:
     https://www.django-rest-framework.org/api-guide/exceptions/#custom-exception-handling
-"""
+"""