Implement more docs website interactive animations

[daquinteroflex]

So recently one thing people liked were the animated open book emojis for the example notebooks as below. I think there are many other places in the tidy3d documentation where we could have this type of interactive features. Of course, we could even do more than just open or close a book.

Screencast.from.18-10-24.16.44.34.webm

It'd be nice to write an example of how this works within these docs so that other teams can reproduce this when autoflex becomes a core docs dependency between the projects. Note that that implementation from within tidy3d needs to be migrated into autoflex. Possibly it'd be good to see even more relevant applications of this in different locations of tidy3d.