Fix typo of name from spectrum to spectrogram
//|
//| Perform a Fast Fourier Transform from the time domain into the frequency domain
//|
-//| See also `~ulab.utils.spectrum`, which computes the magnitude of the fft,
+//| See also `~ulab.utils.spectrogram`, which computes the magnitude of the fft,
//| rather than separately returning its real and imaginary parts."""
//| ...
//|
