docs: add examples for Update-AzSubscription

[matsest]

Description

Adds more examples for the Update-AzSubscription cmdlet (rename and enable)

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate ChangeLog.md file(s) has been updated:
  • For any service, the ChangeLog.md file can be found at src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md
  • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header -- no new version header should be added
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• N/A For public API changes to cmdlets:
  • N/A a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
    • {Please put the link here}
  • N/A the markdown help files have been regenerated using the commands listed here

[ghost]

Thank you for your contribution matsest! We will review the pull request and get back to you soon.

[matsest]

Hope you don't mind me suggesting this - the docs for the cmdlet were not very clear on how this cmdlet supported rename operations (without looking at the source code).

[VeryEarly]

/azp run

[azure-pipelines]

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