Comment by squidfunk

Coming from Material for MkDocs, right now, sources need to be in Markdown files. However, our new build system is extremely flexible, so with the upcoming module system, it will be possible to add further sources and integrate them into the static site generation process. What you mention is part of the feedback we got from talking to organizations, for which Markdown is actually only the target, generated from database records to render a static documentation site.