Does not render footnotes (e.g. gitlab flavored markdown)

[onavhamid]

Issue description

The footnote syntax in GitLab flavored markdown is not supported. Is it possible to support rendering footnotes properly as a PDF?

Steps to reproduce

An example document:

# markdown-pdf-footnote-example

A footnote reference tag looks like this: [^1]

This reference tag is a mix of letters and numbers. [^footnote-42]

[^1]: This is the text inside a footnote.

[^footnote-42]: This is another footnote.

Expected behavior:

(rendered using https://packagecontrol.io/packages/MarkdownPreview - though it is an HTML render)

Actual behavior:

Versions

Ubuntu 20.04

Atom    : 1.46.0
Electron: 4.2.7
Chrome  : 69.0.3497.128
Node    : 10.11.0
npm  6.2.0
node 10.2.1 x64
atom 1.46.0
python 3.7.4
git 2.25.1