feat: add flatpak package description

content/download/index.en.md

@@ -44,10 +44,12 @@ You can also [get the source code](https://code.vikunja.io/frontend) and build i
 ## Desktop apps
 
 The frontend is available as standalone desktop app.
-This allows to use Vikunja without installing a frontend.
+This allows to use Vikunja without deploying a frontend server.
 
 To install it, simply go to [our download server](https://dl.vikunja.io/desktop) choose the latest version and the right variant for your platform.
 
+If you're on Linux, you can also install [the flatpak package](https://flathub.org/apps/io.vikunja.Vikunja).
+
 ## Mobile apps
 
 The app is currently in the early stages of development. Even though it can be used, it might not be stable. If you have bug reports or feature requests, please post them on [this](https://github.com/go-vikunja/app/issues) GitHub page.