As I mentioned, this isn't Google Docs adding full markdown support. Text is converted to Docs' native formatting immediately, meaning there's no way to edit the text in markdown after that.

Learn how to add footnotes and properly formatted citations in Google Docs using built-in features, Google Docs add-ons, and other citation tools.

Click the Add citation source button. Click on the Cite or Insert bibliography button. To get started, open the desired document in Google Docs and click on the Tools > Citations option.