Add link to latest release

Author: simonsmith

README.md

@@ -10,6 +10,7 @@ Read more about [SUIT CSS's design principles](https://github.com/suitcss/suit/)
 ## Installation
 
 * [npm](http://npmjs.org/): `npm install suitcss-components-button`
+* Download: [zip](https://github.com/suitcss/components-button/releases/latest)
 
 ## Available classes