Make visualization in markdown

So excited to share a markdown-it plugin which let you generate a visualization chart using several lines code.

- The project homepage: https://markvis.js.org/ - You can have a try online: https://markvis-editor.js.org/ - Source code: https://github.com/geekplux/markvis

## Motivation

We often publish articles enriched with data, since data make them more convincing and easy to interpret. Hence, techniques that enable the embedding of visualization into texts are of great importance.

However, the most frequently used method now is to export charts as images, upload them into cloud, and then paste them into the editor. It is a tedious process from the perspective of a writer. Besides, image loading costs much more time than that of DOM elements, which leads to poor experience from the perspective of a reader.