fftfreq uses numpy module as example

For documentation of [scipy.fft.fftfreq](https://docs.scipy.org/doc/scipy/reference/generated/scipy.fft.fftfreq.html) the example uses numpy's fft module. Shouldn't it use the scipy one ? 

```python
signal = np.array([-2, 8, 6, 4, 1, 0, 3, 5], dtype=float)
fourier = np.fft.fft(signal)
n = signal.size
timestep = 0.1
freq = np.fft.fftfreq(n, d=timestep)
freq
```