[Improvement] Popup: support lazy render (#1138)

packages/popup/zh-CN.md

@@ -47,6 +47,7 @@ export default {
 | overlay-style | 自定义蒙层样式 | `Object` | `` |
 | close-on-click-overlay | 点击蒙层是否关闭 Popup | `Boolean` | `true` |
 | transition | transition 名称 | `String` | `popup-slide` |
+| lazy-render | 是否在首次显示弹层时才渲染 DOM 节点 | `Boolean` | `true` |
 | get-container | 指定弹出层挂载的 HTML 节点 | `() => HTMLElement` | - |
 
 ### Event