[yocto] Add nfs package to image minimal for atom-pc

[Jack]

Hi,

I built a core-image-minimal for atom-pc. Then, I want to add it nfs and ssh
packages. I added IMAGE_INSTALL_append_pn-core-image-minimal = "
packagegroup-core-ssh-openssh packagegroup-core-nfs" line to local.conf
file. Package packagegroup-core-ssh-openssh was built but I got error for
packagegroup-core-nfs. Error is:

Error: packagegroup-core-nfs not found in the base feeds (atom_pc core2 i686
i586 i486 i386 x86 noarch any all).

How can I solve this error ?
Thanks.