added source for calculated field (assignments)

README.txt

@@ -23,6 +23,7 @@ We truthfully completed this project (this project being Midterm Project: Widget
 References:
 Date-time conversion to timezone in views: https://stackoverflow.com/questions/35072711/django-datetime-field-convert-to-timezone-in-view
 Automatically computed fields: https://stackoverflow.com/questions/17682567/how-to-add-a-calculated-field-to-a-django-model
+Automatically computed fields(1): https://www.youtube.com/watch?v=IkwG2MuUdRo
 Field reference: https://docs.djangoproject.com/en/4.0/ref/models/fields/