Create a warning for OpenSUSE and NixOS due to low package availability

The focus on OpenSUSE and Mullvad puts blinders on this discussion in my opinion. @xra, correct me if I’m wrong, but maybe a simpler solution would be a warning that recommended software may not be packaged for your Linux distribution of choosing. This could be as simple as adding a statement to the first paragraph on the Desktop/PC page. I did look at the Linux Overview page and such a warning didn’t seem to fit the purpose of that page.