/usr/share/doc/libmono-2.0-dev/changelog.Debian.gz is in libmono-2.0-dev 2.10.8.1-1ubuntu2.3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libmono-2.0-dev/../libmono-2.0-1/changelog.Debian.gz