Perhaps you could use double-bracket links like GitHub wikis use, so this would be a [[ubpdk|link to another document]].
IIRC Dokuwiki wasn't too bad either.
Standard Markdown used to lack some important constructs, again IIRC.
Markdown seems perfect for this case where the markup is the rendered content.
Perhaps you could use double-bracket links like GitHub wikis use, so this would be a [[ubpdk|link to another document]].