When a part of the Apache Web Server is marked as experimental, it means that fundamental aspects of it might still change. New releases of this part may not always be backward compatible. In extreme, the part may be scrapped and taken out again.
It's a necessary wriggle room for the project to bring you something new without tying itself up. If you, as user, deploy something experimental, you are willing to participate in that experiment. Maybe because you like the new parts and want to give feedback for improvements. That'd be nice.
Here on github, I bring you experimental experimental versions. These are
tested by me, but not by many else. That is where you come in if you pick up a
mod_md from here.