Fixed #19400 - Typo in docs/topics/auth.txt

    .. method:: models.CustomUserManager.create_superuser(*username_field*, password, **other_fields)

        The prototype of `create_user()` should accept the username field,

        The prototype of `create_superuser()` should accept the username field,

        plus all required fields as arguments. For example, if your user model

        uses `email` as the username field, and has `date_of_birth` as a required

        fields, then create_superuser should be defined as::