Documentation: Add example for plotting a gif

[CSSFrancis]

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name: Add example for plotting a gif

A simple script for plotting an updating gif using matplotlib. This is useful for creating a visualization of some of your data.

This might be a better example in hyperspy but this is pretty much focused on 4-D datasets.

Checklist

• Updated CHANGELOG.md
• Marked as finished

Hopefully this should render in the example as an animation?

[coveralls]

coverage: 94.142%. first build
when pulling 7ec82b4 on CSSFrancis:gif_example
into ba578ff on pyxem:main.

[CSSFrancis]

@ericpre I might move this up to hyperspy as an example? We could take part of @magnunor presentation on making publication quality plots from hyperspy and make that into a set of examples.

I use something like this a fair amount when trying to show a large dataset quickly.

[ericpre]

Yes, this is a long overdue!
There could be examples (simple and advanced) but also a function to export an animation and that allow to compose a matplotlib figure, a bit like the ones in hs.plot.plot_*?