Add Email Design Guide Link

Author: inferjay

README.md

@@ -1257,6 +1257,10 @@ Segmentfault镜像地址：[http://mirrors.segmentfault.com/adchs/](http://mirro
 
 地址：[http://sebastien-gabriel.com/designers-guide-to-dpi/home](http://sebastien-gabriel.com/designers-guide-to-dpi/home#)
 
+#### Email Design Guide
+
+地址：[http://mailchimp.com/resources/email-design-guide/](http://mailchimp.com/resources/email-design-guide/)
+
 ## Free Design Resources
 
 [Google Material Design 素材](http://pan.baidu.com/s/1i35iBNv)(感谢 [@SanityD](http://weibo.com/sanityd))