feat: add popover component

src/popover/README.md

@@ -0,0 +1,32 @@
+# Popover
+
+### Install
+
+```js
+import Vue from 'vue';
+import { Popover } from 'vant';
+
+Vue.use(Popover);
+```
+
+## Usage
+
+### Basic Usage
+
+```html
+
+```
+
+## API
+
+### Props
+
+| Attribute | Description | Type | Default |
+| --------- | ----------- | ---- | ------- |
+
+
+### Events
+
+| Event | Description | Arguments |
+| ----- | ----------- | --------- |
+