Decorator to show fields for api views

I have a api view. I want to show fields in docs. Do we need a decorator to show fields in docs?

```
@api_view(['POST'])
@permission_classes((AllowAny, ))
@throttle_classes([AnonRateThrottle])
@api.doc(fields={'email': 'CharField', 'password':'CharField'})
def change_password(request):
signed_email = request.data.get('email', '')
password = request.data.get('password', '')

try:
email = loads(urlunquote(signed_email))
except BadSignature:
return Response(status=status.HTTP_400_BAD_REQUEST)

if len(password) < 6:
return Response(status=status.HTTP_400_BAD_REQUEST)

if not User.objects.filter(username=email):
return Response(status=status.HTTP_404_NOT_FOUND)

user = User.objects.get(username=email)
user.set_password(password)
user.save()

return Response(status=status.HTTP_200_OK)
```

Start by reviewing the @api_view and @api.doc(fields=...) usage shown in the issue, then inspect the existing API documentation behavior for function-based views. Define how the fields should appear in generated docs and add coverage for the expected result; the issue is done when those fields are documented correctly.

Written by the indexing model from the issue text.