docs(reference): edit reference

ruanyf · web-flow · commit 97e2994e6a33 · 2017-02-10T10:55:46.000+08:00
diff --git a/docs/reference.md b/docs/reference.md
@@ -8,3 +8,4 @@
 - [豌豆荚文案风格指南](https://docs.google.com/document/d/1R8lMCPf6zCD5KEA8ekZ5knK77iw9J-vJ6vEopPemqZM/edit), by 豌豆荚
 - [中文文案排版指北](https://github.com/sparanoid/chinese-copywriting-guidelines), by sparanoid
 - [中文排版需求](http://w3c.github.io/clreq/), by W3C
+- [为什么文件名要小写？](http://www.ruanyifeng.com/blog/2017/02/filename-should-be-lowercase.html), by 阮一峰
