Add documentation for batchChangeJSON

[jhg03a]

Prerequisites

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Description

The cli help tool and readme have no actual documentation as to what batch creation json should look like or references to a VinylDNS api document.

Versions

Found in 0.10.1

[jhg03a]

https://github.com/vinyldns/vinyldns-cli/blob/main/tests/fixtures/batch_change_create_json Is the closest thing that exists as far as I can see in the repo, but that only illustrates what creating an A record would be and you'd have to know to go digging through tests to find it.