update readme

Author: Mike North

README.md

@@ -4,6 +4,8 @@ A Chrome Extension to enhance package manifests in github
 
 ![Screenshot](https://raw.githubusercontent.com/truenorth/chrome-github-boxcutter/master/screenshot.jpg)
 
+### [Download it](https://chrome.google.com/webstore/detail/github-boxcutter/knapnimomamjogbajmmoefhopnebjbff)
+
 ## License
 
 Please don't copy this for now. I may license it in the future