Region Controller is unclear

It is unclear if a region controller can be part of a regular deployment, or should be a discrete deployment in and of itself.

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Document: how-to/misc/multiregion-deployments.rst

Start by reading how-to/misc/multiregion-deployments.rst and the surrounding guidance on region controllers and deployments. Clarify whether a region controller belongs in a regular deployment or requires a discrete deployment, so the document gives an explicit, unambiguous answer.

Written by the indexing model from the issue text.