/usr/share/man/man5/xorg.conf.d.5.gz is in xserver-xorg-core 2:1.15.1-0ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man5/xorg.conf.5.gz
/usr/share/man/man5/xorg.conf.5.gz