DOC: update thresholding docstring to reflect complex-valued support
DOC: update thresholding docstring to reflect complex-valued support

rgommers/pywt,PyWavelets/pywt,PyWavelets/pywt,rgommers/pywt,grlee77/pywt,rgommers/pywt,rgommers/pywt,grlee77/pywt