update sovereign cloud doc to promote the cloud_setting feature.

[xiangyan99]

We also need MicrosoftDocs/python-sdk-docs-examples#39

[prmerger-automator]

@xiangyan99 : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[learn-build-service-prod]

Learn Build status updates of commit eb6001c:

⚠️ Validation status: warnings

File	Status	Preview URL	Details
articles/python/sdk/azure-sdk-sovereign-domain.md	⚠️Warning		Details

articles/python/sdk/azure-sdk-sovereign-domain.md

• Line 32, Column 1: [Warning: invalid-code] The code snippet "~/../python-sdk-docs-examples/sovereign_domain/sovereign_cloud_old.py" could not be found.

For more details, please refer to the build report.

Note: Your PR may contain errors or warnings or suggestions unrelated to the files you changed. This happens when external dependencies like GitHub alias, Microsoft alias, cross repo links are updated. Please use these instructions to resolve them.

[mcleanbyron]

@bobtabor-msft FYI

[v-dirichards]

@bobtabor-msft

Can you review the proposed changes?

Important: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team

[KarlErickson]

@bobtabor-msft ping

[bobtabor-msft]

#sign-off