/usr/lib/mpich-mpd/man/man3 is in mpich-mpd-bin 1.2.7-10ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/mpich-mpd/man/../../../share/man/man3
/usr/lib/mpich-mpd/man/../../../share/man/man3