You probably can't, the markdown plugin took a while to become GTK3 capable, so from when Debian/Ubuntu switched to GTK3 and the release with markdown GTK3 compatible its not available.
When Debian/Ubuntu catches up with a recent version of Geany-plugins it should appear again (assuming the package maintainer for those distros remembers to re-enable it if its manual). -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/geany/geany-plugins/issues/982#issuecomment-631871253
