add npm install instructions and badge to README

Author: baseten

README.md

@@ -1,3 +1,5 @@
+[![npm version](https://badge.fury.io/js/react-css-transform.svg)](https://badge.fury.io/js/react-css-transform)
+
 # React CSS Transform
 
 A helper library to handle nested 2D and 3D CSS transforms using matrix multiplication, 
@@ -7,6 +9,10 @@ combinations of nested transformations trivial.
 `<Transform2d>` was initially developed while I was working at [Pest Pulse](https://www.pestpulse.com/) 
 for a zoomable/pannable map with markers.
 
+Get started:
+
+`npm install gl-matrix react-css-transform --save`
+
 More docs coming soon!
 
 [3D Cubes Example](https://baseten.github.io/react-css-transform/3d-cubes/index.html)