Documentation: emphasize need for importing Animate.css

[nienkedekker]

First off, thank you for your great library! It's really useful. However, reading the documentation, it wasn't clear to me that I had to manually import animate.css in my CSS. Animations weren't working until I added @import '../../../node_modules/animate.css/animate.css' to my master scss file.

Perhaps you could add this to your documentation! Cheers!

[jonhue]

Good call!