message: docs(DropdownMenu): add demo of active-color
diff: @@ -77,6 +77,17 @@ export default {
  };
  ```
  +### Custom Active Color
  +
  +Use `active-color` prop to custom active color of the title and options
  +
  +```html
  +<van-dropdown-menu active-color="#f44">
  + <van-dropdown-item v-model="value1" :options="option1" />
  + <van-dropdown-item v-model="value2" :options="option2" />
  +</van-dropdown-menu>
  +```
  +
  ### Expand Direction
  ```html
  