+ survivejs-webpack book link

http://survivejs.com/blog/survivejs-webpack-100/

Disclosure: I've worked with [Juho before](https://github.com/jsdelivr/api/graphs/contributors).  But frankly, I lost track of him; & found his blog via Google search, so he knows nothing about this PR before now.

README.md

@@ -269,6 +269,8 @@ MIT (http://opensource.org/licenses/mit-license.php)
 
 This is a free-time project. The time I invest in it fluctuates. If you use webpack for a serious task, and you'd like me to invest more time on it, please donate. This project increases your income/productivity too. It makes development and applications faster and it reduces the required bandwidth.
 
+Another way you can help fund Webpack is by buying the ebook ["SurviveJS - Webpack"](https://leanpub.com/survivejs-webpack), where around ~30% of the book's profit will go to me.
+
 I'm very thankful for every dollar. If you leave your username or email, I may show my thanks by giving you extra support.