xournal: add license info

+1
+1
pkgs/applications/graphics/xournal/default.nix
··· 25 homepage = http://xournal.sourceforge.net/; 26 description = "note-taking application (supposes stylus)"; 27 maintainers = [ stdenv.lib.maintainers.guibert ]; 28 }; 29 }
··· 25 homepage = http://xournal.sourceforge.net/; 26 description = "note-taking application (supposes stylus)"; 27 maintainers = [ stdenv.lib.maintainers.guibert ]; 28 + license = stdenv.lib.licenses.gpl2; 29 }; 30 }