Gh-192: Federated Store Guide (#416)

* Import Federated Store Walkthough from old docs and update
This is no longer called a walkthrough. Some content is now part of the separate Federated Operation guide.

* PR Comments

* Further PR comments

* Fix typo

* Apply suggestions from code review

Co-authored-by: tb06904 <[email protected]>

* Corrected propery name due to Gaffer change

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Co-authored-by: tb06904 <[email protected]>
Co-authored-by: t92549 <[email protected]>