hexo-renderer-markdown-it里的插件使用

hexo-renderer-markdown-it 默认集成5个 markdown-it 插件

# Markdown-it config
markdown:
  plugins:
    - markdown-it-abbr
    - markdown-it-footnote
    - markdown-it-ins
    - markdown-it-sub
    - markdown-it-sup

• markdown-it-abbr：缩写插件

*[HTML]: Hyper Text Markup Language
*[W3C]:  World Wide Web Consortium

The HTML specification
is maintained by the W3C.

• markdown-it-footnote：脚注插件

basic footnote[^1]
and another one[^3]
and another one[^4]

[^1]: basic footnote content
[^3]: paragraph
[^4]: footnote content with some [markdown](https://en.wikipedia.org/wiki/Markdown)

• markdown-it-ins：插入插件（下划线插件）

++inserted++ => <ins>inserted</ins>

• markdown-it-sub：下标插件

H~2~0 => H<sub>2</sub>O

• markdown-it-sup：上标插件

29^th^ => 29<sup>th</sup>

• markdown-it-mark：高亮插件（需要自己下载）

  ==marked==` => `inserted