README.md: Update a bit
README.md: Update a bit

mdshuai/rpm-ostree,mdshuai/rpm-ostree,tmp-user/rpm-ostree,giuseppe/rpm-ostree,giuseppe/rpm-ostree,giuseppe/rpm-ostree,tmp-user/rpm-ostree,tmp-user/rpm-ostree,giuseppe/rpm-ostree,mdshuai/rpm-ostree,mdshuai/rpm-ostree,tmp-user/rpm-ostree