auth.md: unclear description in section 4 (sending answers) point 4: "there is a node"

[auerswal]

The last point in section 4, Sending answers, of auth.md is confusing:

From best zone, the name may exist, but there is a node or a parent has an NS record. Send delegation

The "there is a node" part seems either wrong or incomplete. The possible meanings could be "there is no node," or "there is a node with NS RRs" (inferring from section 5), but this is not clear without knowing what this documentation intends to teach. It might be something else entirely. I do not know.