Add Downloads badge

Signed-off-by: martinRenou <[email protected]>

Author: martinRenou

README.md

@@ -5,6 +5,7 @@
 [![Documentation](http://readthedocs.org/projects/ipycanvas/badge/?version=latest)](https://ipycanvas.readthedocs.io/en/latest/?badge=latest)
 [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/martinRenou/ipycanvas/stable?filepath=examples)
 [![Build Status](https://travis-ci.org/martinRenou/ipycanvas.svg?branch=master)](https://travis-ci.org/martinRenou/ipycanvas)
+[![Downloads](https://pepy.tech/badge/ipycanvas)](https://pepy.tech/project/ipycanvas)
 
 ipycanvas is a lightweight, fast and stable library exposing the [browser's Canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API) to IPython.
 It allows you to draw simple primitives directly from Python like text, lines, polygons, arcs, images etc. This simple toolset allows you to draw literally anything!