Cext-5659 corrected region selection behavior for ABDB

[nofuss]

Description

Corrected the description of how database regions are specified in the app.config.yaml manifest, the db plugin for the aio cll and the aio-lib-db library.

Related Issue

https://jira.corp.adobe.com/browse/CEXT-5659

Motivation and Context

Previous documentation incorrectly describe the behavior.

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[keharper]

The linting errors are not due to anything in the changed file.