/usr/share/doc/linux-tools-4.15.0-15-generic/changelog.Debian.gz is in linux-tools-4.15.0-15-generic 4.15.0-15.16~16.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/linux-tools-4.15.0-15-generic/../linux-hwe-edge-tools-4.15.0-15/changelog.Debian.gz