README animation gif example is now up to date

[GenevieveBuckley]

I noticed the animation screencast on the README page had some deprecated code visible in the gif, so I've updated it.

Now the README has:

• A complete code snippet you can copy-paste and run immediately
• A cropped version of the gif, that doesn't show the notebook cell with the old & deprecated animate_glpyhs command, which has been superseded by animation_control

Here's a static screenshot of the revised section:

[maartenbreddels]

That is super nice!!!
Could you maybe put the gif in this issue:
#15
so we don't have to put the .gif in the repo (otherwise it gets super large)

[GenevieveBuckley]

Done. Is issue #15 the right place to put the other two gifs in misc/ as well?

[maartenbreddels]

yeah, put any gif you want there, it's better for not growing the repo too much.