docs, model updates, add tests, add documentation (#16)

* docs, model updates, add tests, add documentation

* add explicit tests for validation test fix, add changelog

* docs and update

* add decision log entry for different grains

* bk

* vertical integration test

* packages.yml

---------

Co-authored-by: Jamie Rodriguez <65564846+fivetran-jamie@users.noreply.github.com>

Merge pull request #11 from fivetran/MagicBot/add-union-schema

Feature: Union schema compatibility

Merge pull request #6 from fivetran/feature/api-v3-updates

feature/api-v3-updates

Update packages.yml