/usr/share/man/man8/libnss_systemd.so.2.8.gz is in libnss-systemd 237-3ubuntu10.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man8/nss-systemd.8.gz
/usr/share/man/man8/nss-systemd.8.gz