SVG's SMIL animations are deprecated

Maybe warns people in the readme about the depreciation of the SVG's SMIL animations (Chrome, FF)

https://developer.mozilla.org/fr/docs/Web/SVG/SVG_animation_with_SMIL

> As of Chrome 45.0, SMIL animations are deprecated in favor of CSS animations and Web animations.

http://stackoverflow.com/questions/30965580/deprecated-smil-svg-animation-replaced-with-css-or-web-animations-effects-hover
