/usr/share/doc/libcgns-dev/README.gz is in libcgns-dev 2.5.5-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libcgns-dev/../libcgns2/README.gz
/usr/share/doc/libcgns-dev/../libcgns2/README.gz