ws-3314: logo dark and light version

Author: Adam Soos

README.md

@@ -1,4 +1,11 @@
-<a href="https://www.babelstreet.com/rosette"><img src="https://charts.babelstreet.com/icon.png" width="47" height="60"/></a>
+<a href="https://www.babelstreet.com/rosette">
+<picture>
+  <source media="(prefers-color-scheme: light)" srcset="https://charts.babelstreet.com/icon-dark.png">
+  <source media="(prefers-color-scheme: dark)" srcset="https://charts.babelstreet.com/icon-light.png">
+  <img alt="Babel Street Logo" width="48" height="48">
+</picture>
+</a>
+
 # Analytics by Babel Street
 
 [![Packagist](https://img.shields.io/packagist/v/rosette/api.svg?colorB=bright%20green&style=flat)](https://packagist.org/packages/rosette/api)