[Doc] props title

packages/picker/en-US.md

@@ -134,7 +134,7 @@ When Picker columns data is acquired asynchronously, use `loading` prop to show
 <van-picker :columns="columns" loading />
 ```
 
-### API
+### Props
 
 | Attribute | Description | Type | Default |
 |------|------|------|------|
@@ -149,7 +149,7 @@ When Picker columns data is acquired asynchronously, use `loading` prop to show
 | visible-item-count | Count of visible columns | `Number` | `5` |
 | default-index | Default value index of single column picker | `Number` | `0` |
 
-### Event
+### Events
 Picker events will pass different parameters according to the columns are single or multiple
 
 | Event | Description | Arguments |
@@ -158,7 +158,7 @@ Picker events will pass different parameters according to the columns are single
 | cancel | Triggered when click cancel button | Single column：current value，current index<br>Multiple columns：current values，current indexes |
 | change | Triggered when current option changed | Single column：Picker instance, current value，current index<br>Multiple columns：Picker instance, current values，column index |
 
-### Slot
+### Slots
 
 | Name | Description |
 |------|------|

packages/picker/zh-CN.md

@@ -143,7 +143,7 @@ export default {
 <van-picker :columns="columns" loading />
 ```
 
-### API
+### Props
 
 | 参数 | 说明 | 类型 | 默认值 | 版本 |
 |------|------|------|------|------|
@@ -158,7 +158,7 @@ export default {
 | visible-item-count | 可见的选项个数 | `Number` | `5` | - |
 | default-index | 单列选择器的默认选中项索引，<br>多列选择器请参考下方的 Columns 配置 | `Number` | `0` | 1.6.9 |
 
-### Event
+### Events
 
 Picker 组件的事件会根据 columns 是单列或多列返回不同的参数
 
@@ -168,7 +168,7 @@ Picker 组件的事件会根据 columns 是单列或多列返回不同的参数
 | cancel | 点击取消按钮时触发 | 单列：选中值，选中值对应的索引<br>多列：所有列选中值，所有列选中值对应的索引 |
 | change | 选项改变时触发 | 单列：Picker 实例，选中值，选中值对应的索引<br>多列：Picker 实例，所有列选中值，当前列对应的索引 |
 
-### Slot
+### Slots
 
 | 名称 | 说明 |
 |------|------|