The current behavior is to create a .txt file, despite the editor supporting markdown as a use-case. It kinda sucks, because it will rename my files from .md to .txt, unless I name the title of the document the filename (first line should be 'filename.md'). This is a welcome addition!
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko