[DNS] Fix DNS delegation wording in nameservers documentation

[matilde-cf]

Summary

Fixes technical inaccuracy in the DNS delegation explanation for subdomain setup in the nameservers documentation.

The previous wording incorrectly stated "the child domain has been delegated to the parent domain," which is backwards. In DNS delegation, the parent zone delegates authority to a child zone by creating NS records for it.

Change made:

• Updated the sentence to correctly state: "the parent domain (example.com) must delegate authority to the child domain"

Screenshots (optional)

N/A - Text correction only

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