/usr/share/doc/gnustep-make/Developer is in gnustep-make-doc 2.6.2-2.1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gnustep-make/../../GNUstep/Documentation/Developer
/usr/share/doc/gnustep-make/../../GNUstep/Documentation/Developer