Remove "free and secure" from Discord description (#40968)

* Remove "free and secure" from Discord description

Changed Discord package description to remove "free and secure". We can't vouch for its security, but it's definitely not "free" in the sense that most users would read this description. ;)

* Add "cross-platform" to Discord description

pkgs/applications/networking/instant-messengers/discord/default.nix

···
     };
 
     meta = with stdenv.lib; {
-        description = "All-in-one voice and text chat for gamers that’s free, secure, and works on both your desktop and phone";
+        description = "All-in-one cross-platform voice and text chat for gamers";
         homepage = https://discordapp.com/;
         downloadPage = "https://github.com/crmarsh/discord-linux-bugs";
         license = licenses.unfree;