设置「动画效果」 use-motion -->motion

http://theme-next.iissnan.com/theme-settings.html#use-motion
设置动画效果部分

```
use_motion: true # 开启动画效果
use_motion: false # 关闭动画效果

motion:
enable: false
async: false
transition:
```

Open the linked theme-settings.html#use-motion section and compare it with the configuration snippet in this issue. Identify the source for that documentation section, clarify how use_motion and the motion options should be described, and confirm the rendered section reflects the agreed settings.

Written by the indexing model from the issue text.