Merge pull request #16090 from ant-design/docs

docs: Add responsive polyfill of Grid FAQ

components/grid/index.en-US.md

@@ -112,3 +112,9 @@ If the Ant Design grid layout component does not meet your needs, you can use th
 | xxl | `≥1600px`, could be a `span` value or an object containing above props | number\|object | - |
 
 The breakpoints of responsive grid follow [BootStrap 4 media queries rules](https://getbootstrap.com/docs/4.0/layout/overview/#responsive-breakpoints)(not including `occasionally part`).
+
+## FAQ
+
+### How to support IE9 when using responsive?
+
+You can use [matchMedia polyfill](https://github.com/paulirish/matchMedia.js/) to handle this.

components/grid/index.zh-CN.md

@@ -111,3 +111,9 @@ Ant Design 的布局组件若不能满足你的需求，你也可以直接使用
 | xxl | `≥1600px` 响应式栅格，可为栅格数或一个包含其他属性的对象 | number\|object | - |
 
 响应式栅格的断点扩展自 [BootStrap 4 的规则](https://getbootstrap.com/docs/4.0/layout/overview/#responsive-breakpoints)（不包含链接里 `occasionally` 的部分)。
+
+## FAQ
+
+### IE9 响应式不工作怎么办？
+
+可以引入 [matchMedia polyfill](https://github.com/paulirish/matchMedia.js/) 添加支持。