update Changelog

CHANGELOG.en-US.md

@@ -38,6 +38,7 @@ If you want to read change logs before `2.0.0`, please visit [GitHub](https://gi
   * Fixed duplication `onChange` callback. [#156@rc-select](https://github.com/react-component/select/pull/156)
   * Fixed displaying of initial value. [#152@rc-select](https://github.com/react-component/select/pull/152)
 * Upgrade rc-tree-select to `1.9.0`, fixed an overflow-wrap issue of TreeSelect. [#42@rc-tree-select](https://github.com/react-component/tree-select/pull/42)，[#43@rc-tree-select](https://github.com/react-component/tree-select/pull/43)
+* Added less variables: `@border-style-base` `@border-width-base` `@btn-danger-color` `@btn-danger-bg` and etc.
 
 ## 2.6.4
 

CHANGELOG.zh-CN.md

@@ -38,6 +38,7 @@ timeline: true
   * 修复了 Select 的 `onChange` 回调重复触发的问题。[#156@rc-select](https://github.com/react-component/select/pull/156)
   * 修复了 Select 显示初始化值的问题。[#152@rc-select](https://github.com/react-component/select/pull/152)
 * 升级了 rc-tree-select 到 1.9.0，修复了 TreeSelect 的文字溢出换行问题 [#42@rc-tree-select](https://github.com/react-component/tree-select/pull/42)，[#43@rc-tree-select](https://github.com/react-component/tree-select/pull/43)
+* 新增 less 变量: `@border-style-base` `@border-width-base` `@btn-danger-color` `@btn-danger-bg` 等。
 
 ## 2.6.4