Unable to write a description for a serializer that extends serializers.ChoiceField using docstrings

[ldeluigi]

Describe the bug
While I can use python docstrings to customize the text description of my serializers, I have one that I can't. That's the only one inheriting from serializers.ChoiceField.

To Reproduce

class MySerializer(serializers.ChoiceField):
    '''i want this to appear in the swagger schema'''
    def __init__(self, **kwargs):
        super().__init__(MyChoices.choices, **kwargs)

Expected behavior
The docstring should appear as description in the openapi schema, but it doesn't