/usr/share/man/man5/pam.d.5.gz is in libpam-runtime 1.1.3-7ubuntu2.3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man5/pam.conf.5.gz
/usr/share/man/man5/pam.conf.5.gz