My apologies for not crediting the author of this script as it is not me.
tell application id "DNtp"
set the clipboard to "[" & the name of the content record & "](" & the reference URL of the content record & ")"
end tell
(* In Highlights, in the righthand pane, click "Edit" to see the Markdown text of your annotations and notes. Paste the clipboard (⌘V) where shown here -- replacing
[Link](http://example.com) *)