Jeff this is not a good idea. Come up with a new name and proceed with excellence.
Otherwise someone else is going to do what you’re doing, in parallel, and they will claim to be the one true boss of Markdown, and then before you know it Markdown, which now means something, despite your saying otherwise, will mean nothing.
We all use Markdown, not just you and your pals. It isn’t yours to do with as you please. Create something new, and respect prior art. That’s fantastic.