update CHANGELOG.md

CHANGELOG.md

+## 2.0.4
+
+`2019-3-12`
+
+* :sparkles: 新增构建CommonJS包
+* :sparkles: 新增倒计时`CountDown`组件
+* :bug: 修复`Rate`组件样式兼容问题
+* :bug: 修复两个组件测试用例问题
+* :zap: 优化`Swiper`组件
+* :zap: 文档增加目录功能
+* :zap: 新增英文版README.md
+
 ## 2.0.3
 
 `2019-1-25`

package.json

 {
   "name": "@nutui/nutui",
-  "version": "2.0.3",
+  "version": "2.0.4",
   "description": "一套轻量级移动端Vue组件库",
   "typings": "dist/types/index.d.ts",
   "main": "dist/nutui.js",