Support for footnote syntax

[colindean]

I'd love to see support for footnotes, e.g.

The system can only support single-environment deployment.
This limits our capacity.
While we work on a solution[^prod_pr_open],
we'll continue to adjust resources in the primary environment.


[^prod_pr_open]: Work for deployment to multiple environments exists in a draft PR.

renders as such in GitHub, GitLab, goldmark, pandoc, and others (but is not yet a part of Commonmark):

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The system can only support single-environment deployment.
This limits our capacity.
While we work on a solution¹,
we'll continue to adjust resources in the primary environment.

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Footnotes

1. Work for deployment to multiple environments exists in a draft PR. ↩