modules/nfs.nix: /mnt/caddy-certs -> /mnt/certs
For some reason having the mount point be named /mnt/caddy-certs
doesn't always work.
Nix seems to not be able to create the mount unit for systemd which
causes systemd to fail when trying to mount it and this prevents
rebuilds in such a way that I have to reboot in order to rebuild the
configuration again otherwise the system will try to unmount the mount
unit that doesn't exist and just continue to fail.