🤔 [QUESTION]markerPoints属性是删除了吗？

### 🐛 Question description [Please make everyone to understand it]
markerPoints我看只有在https://antv-g2plot-v1.gitee.io/zh/examples/line/marker#basic这里能够展示出来，但是在线网站展示不出来，https://stackblitz.com/run?file=index.js
### 💻 Link to minimal reproduction

Please provide a link by forking these links [g2plot](https://codesandbox.io/s/g2plot-reproduction-template-gyej1) or GitHub repo. What is a minimal reproduction, and why is it required?

### 🏞 Expected result

### 🚑 Any additional [like screenshots]

* **G2Plot Version**:
* **Platform**:

Start with the linked StackBlitz reproduction at index.js and compare its markerPoints behavior with the linked G2Plot v1 line-marker example. Confirm the G2Plot version and platform, then determine whether markerPoints should render on the online example or whether its removal needs to be clarified.

Written by the indexing model from the issue text.