Man pages matching name umount.nfs in section 8:

umount.nfs.8.en	debian 10 / nfs-common
umount.nfs.8.de	debian 11 / manpages-de
umount.nfs.8.fr	debian 11 / manpages-fr
umount.nfs.8.en	debian 11 / nfs-common
umount.nfs.8.de	debian 12 / manpages-de
umount.nfs.8.fr	debian 12 / manpages-fr
umount.nfs.8.en	debian 12 / nfs-common