I am trying to modify ox-md.el. I do not know too much emacs lisp so please bear with me.
Hypothetically, if I want to modify the exporter to add a "THIS DOCUMENT BY: " at the beginning, could I do:
(defun org-md-template (contents info)
"Return complete document string after Markdown conversion.
CONTENTS is the transcoded contents string. INFO is a plist used
as a communication channel."
(concat "THIS DOCUMENT BY: " (plist-get info :author) "\n" contents)