/usr/share/doc/postgresql-9.4/README.Debian.gz is in postgresql-9.4 9.4.18-0+deb8u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/postgresql-9.4/../postgresql-common/README.Debian.gz
/usr/share/doc/postgresql-9.4/../postgresql-common/README.Debian.gz