hope to get sample in html text

[xiuhe1210]

• I have searched the issues of this repository and believe that this is not a duplicate.

What problem does this feature solve?

Examples lack of Html-like Code
as a product Designer, I use G2 sample code with modified in AXure to explain my thoughts , and I find there is no sample html code in new version.

作为一个PD，我在日常会使用G2的html样例，稍微做一些数据调整，嵌入Axure中，就可以很好的表达我的诉求，因为动效都有，研发的同学也可以很好的理解我的意图，但是我目前发现在最新的sample中，html的样例没有了，希望可以添加回来。

What does the proposed API look like?

• 希望有html的代码在右侧展示，类似2018的版本一样（事实上，我很担心后面2018会被下掉,404 not found....）
• examples(Eg. https://g2.antv.vision/en/examples/gallery/line ) with html-like Code in right side

[simaQ]

目前你可以继续访问我们的旧网址：https://antv-2018.alipay.com/zh-cn/g2/3.x/demo/index.html

[simaQ]

功能已添加