Bug report

Bug summary

the docstring of parameter Fs of matplotlib.pyplot.specgram() says that the default value is 2 but the default value in the function signature is None.

Code for reproduction

point your browser to https://matplotlib.org/devdocs/api/_as_gen/matplotlib.pyplot.specgram.html or do:

import matplotlib.pyplot as plt
help(plt.specgram)

Actual outcome

specgram(x, NFFT=None, Fs=None, Fc=None, ...
...
Fs : scalar
        The sampling frequency (samples per time unit).  It is used
        to calculate the Fourier frequencies, freqs, in cycles per time
        unit. The default value is 2.

Expected outcome

Either write None in the docstring or make change the default value of Fs to 2.

Matplotlib version

• Operating System: OSX 10.11.6
• Matplotlib Version: 2.0.2
• Python Version: 3.5.4
• Jupyter Version (if applicable): notebook server 5.0.0, IPython 6.1.0
• Other Libraries: N/A

Installed with pip in a conda environment.