fix: Style variables describe error , close #6009 (#6027)

Co-authored-by: wanjun.shi <[email protected]>

Author: shiwanjun1995

site/src/vueDocs/customize-theme.en-US.md

@@ -23,7 +23,7 @@ There are some major variables below, all less variables could be found in [Defa
 @text-color: rgba(0, 0, 0, 0.85); // major text color
 @text-color-secondary: rgba(0, 0, 0, 0.45); // secondary text color
 @disabled-color: rgba(0, 0, 0, 0.25); // disable state color
-@border-radius-base: 4px; // major border radius
+@border-radius-base: 2px; // major border radius
 @border-color-base: #d9d9d9; // major border color
 @box-shadow-base: 0 2px 8px rgba(0, 0, 0, 0.15); // major shadow for layers
 ```

site/src/vueDocs/customize-theme.zh-CN.md

@@ -23,7 +23,7 @@ antd 的样式使用了 [Less](http://lesscss.org/) 作为开发语言，并定
 @text-color: rgba(0, 0, 0, 0.65); // 主文本色
 @text-color-secondary: rgba(0, 0, 0, 0.45); // 次文本色
 @disabled-color: rgba(0, 0, 0, 0.25); // 失效色
-@border-radius-base: 4px; // 组件/浮层圆角
+@border-radius-base: 2px; // 组件/浮层圆角
 @border-color-base: #d9d9d9; // 边框色
 @box-shadow-base: 0 2px 8px rgba(0, 0, 0, 0.15); // 浮层阴影
 ```