message: docs(Search): update demo
diff: @@ -14,7 +14,7 @@ Vue.use(Search);
  ### Basic Usage
  ```html
  -<van-search placeholder="Placeholder" v-model="value" />
  +<van-search v-model="value" placeholder="Placeholder" />
  ```
  ```js
  @@ -24,41 +24,75 @@ export default {
  }
  }
  ```
  -### Custom Background Color
  +
  +### Listen to Events
  +
  +`search` event will be triggered when click the search button on the keyboard, `cancel` event will be triggered when click the cancel button.
  ```html
  -<van-search placeholder="Placeholder" v-model="value" background="#c8c9cc"/>
  +<form action="/">
  + <van-search
  + v-model="value"
  + show-action
  + placeholder="Placeholder"
  + @search="onSearch"
  + @cancel="onCancel"
  + />
  +</form>
  ```
  -### Disable Search Bar
  +```js
  +import { Toast } from 'vant';
  -```html
  -<van-search placeholder="Placeholder" v-model="value" disabled/>
  +export default {
  + data() {
  + return {
  + value: ''
  + };
  + },
  + methods: {
  + onSearch(val) {
  + Toast(val);
  + },
  + onCancel() {
  + Toast('Cancel');
  + }
  + }
  +}
  ```
  -### Search Bar Content Alignment
  +> Tips: There will be a search button on the keyboard when Search is inside a form in iOS.
  +
  +### Input Align
  ```html
  -<van-search placeholder="Placeholder" v-model="value" input-align="center"/>
  +<van-search
  + v-model="value"
  + input-align="center"
  + placeholder="Placeholder"
  +/>
  ```
  -### Listen to Events
  -
  -`search` event will be triggered when click the search button on the keyboard, `cancel` event will be triggered when click the cancel button.
  +### Disabled
  ```html
  -<form action="/">
  <van-search
  v-model="value"
  + disabled
  placeholder="Placeholder"
  - show-action
  - @search="onSearch"
  - @cancel="onCancel"
  />
  -</form>
  ```
  -> Tips: There will be a search button on the keyboard when Search is inside a form in iOS.
  +### Custom Background Color
  +
  +```html
  +<van-search
  + v-model="value"
  + shape="round"
  + background="#4fc08d"
  + placeholder="Placeholder"
  +/>
  +```
  ### Custom Action Button
  