update(doc): drawer add position dependency

Author: dolymood

document/components/docs/en-US/drawer.md

@@ -2,6 +2,8 @@
 
 Drawer, this component is used to select item in many items, it used full-page panels to interaction normally.
 
+__Notice:__ Drawer component's container element should be be a relative or absolute position element.
+
 ### Demo
 
 - Default usage

document/components/docs/zh-CN/drawer.md

@@ -2,6 +2,8 @@
 
 抽屉，主要用来需要大范围层级进行选择的场景，一般情况下应该是满屏状态。
 
+__注：__ 组件依赖父容器相对定位或者绝对定位，因为 Drawer 是绝对定位的。
+
 ### 示例
 
 - 默认配置使用