/usr/share/man/man8/rpc.nfsd.8.gz is in nfs-kernel-server 1:1.2.8-6ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man8/nfsd.8.gz
/usr/share/man/man8/nfsd.8.gz