Add option to customize back reference aria-label text

[SebastianKohler]

• Extension Name: marked-footnote
• Extension Version: 1.2.4

Use case

Markdown texts with footnotes in non-English languages.

Proposal

Add an option to customize the aria-label text of footnote back references. Currently the aria-labels are hard coded as Back to reference #. The "Back to reference" part should be customizable, so the back reference links don't have aria-labels in English if the text is otherwise in another language.

Being able to customize description is already a great feature!