adding plt.show() to show plots

[paul-cb]

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Title:
Small add to preview plot, it currently doesn't have it.
Summary:

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[dwierichs]

Hi @paul-cb , happened to come across this PR. Is this something we need to add in demos? It seems that the plot shows up fine on the rendered demo? 🤔

[paul-cb]

Hi @dwierichs, I agree it renders fine but when the notebook is downloaded via link on the left on the site this line of code to view the plot is not present actually.