doc: Restore treefile.md docs
doc: Restore treefile.md docs

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