外部链接的渲染格式不符合预期

[Martzki]

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Issue Checklist

• I am using the latest version of hexo-theme-ayer.
• I have reviewed the latest Roadmap on GitHub and searched for current Ayer Issues, which does not help me.

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Expected behavior

渲染出来的格式为带中括号的上标小数字，就像这样：test¹

Actual behavior

渲染出来的格式为上标数字，带^，如：test ^1

• Links to demo site with this issue: demo
• Links to repository or source code of the blog: repository

Steps to reproduce the behavior

1. markdown中使用[^1]这类外部链接语法

Environment Information

Node.js and NPM Information

N/A

Package dependencies Information

N/A

HTML Configuration

N/A

Other Information

N/A

Footnotes

1. test ↩

[welcome]

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