python310Packages.furo: add changelog to meta

pkgs/development/python-modules/furo/default.nix

···
   meta = with lib; {
     description = "A clean customizable documentation theme for Sphinx";
     homepage = "https://github.com/pradyunsg/furo";
+    changelog = "https://github.com/pradyunsg/furo/blob/${version}/docs/changelog.md";
     license = licenses.mit;
     maintainers = with maintainers; [ Luflosi ];
   };