Right now old cookbook webpages don't clearly indicate when they're not the latest version. This may be problematic as Google frequently sends people to old cookbooks.

Perhaps mimic the warning like SciPy uses:
https://docs.scipy.org/doc/scipy-1.0.0/reference/generated/scipy.signal.hanning.html