/usr/share/doc/libgtkmm-2.4-dbg/README is in libgtkmm-2.4-dbg 1:2.24.4-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgtkmm-2.4-dbg/../libgtkmm-2.4-1v5/README
/usr/share/doc/libgtkmm-2.4-dbg/../libgtkmm-2.4-1v5/README