<<<
--- django/db/models/fields/__init__.py
+++ django/db/models/fields/__init__.py
@@ -2034,6 +2034,10 @@
     description = _("Duration")
 
     def __init__(self, *args, **kwargs):
+        if 'help_text' not in kwargs:
+            kwargs['help_text'] = _("Enter duration in the format: [DD] [[HH:]MM:]ss[.uuuuuu]")
         super().__init__(*args, **kwargs)
 
     def get_internal_type(self):
>>>