/usr/share/man/man8/update-grub2.8.gz is in grub2-common 2.02~beta2-36ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man8/update-grub.8.gz
/usr/share/man/man8/update-grub.8.gz