owncloudclient: add license

see issue #43716

+1
+1
pkgs/applications/networking/owncloud-client/default.nix
··· 25 25 homepage = https://owncloud.org; 26 26 maintainers = [ maintainers.qknight ]; 27 27 platforms = platforms.unix; 28 + license = licenses.gpl2Plus; 28 29 }; 29 30 }