chore(nix): add meta.mainProgram attribute

Signed-off-by: seth <[email protected]>

Author: getchoo

nix/pkg/default.nix

@@ -58,6 +58,7 @@ assert lib.assertMsg (stdenv.isLinux || !gamemodeSupport) "gamemodeSupport is on
     dontWrapQtApps = true;
 
     meta = with lib; {
+      mainProgram = "prismlauncher";
       homepage = "https://prismlauncher.org/";
       description = "A free, open source launcher for Minecraft";
       longDescription = ''