Add flatpak as a download option

[hfiguiere]

I submitted LDView for inclusion on Flathub to be installed as a flatpak.

See flathub/flathub#2844

When it is available there, it would be nice to have this option listed for Linux user to install LDView.

Also let me know if you want to be added to the repository so you can update (not required, but we like to give the option to upstream developers).

There are already a couple of other LEGO app on Flathub, like LeoCAD and LPub3D.

[pbartfai]

Flatpak added to the download list. See https://tcobbs.github.io/ldview/Downloads.html

@hfiguiere
Please add me to the repository.

May I close this issue?

[pbartfai]

Let's verify the Flathub app.

[hfiguiere]

Please file a request there https://github.com/flathub/flathub/issues/new for access.