Updating the warning message to match that of portal UI

[bganapa]

Description

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate change log has been updated
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • the changes have gone through a cmdlet design review (Microsoft internal partners only)
  • the cmdlet markdown files were generated using the platyPS module

[deathly809]

@jacobb42 For review as well.

[deathly809]

@bganapa We need to update release notes to say "Only supported on 1810"

[bganapa]

@deathly809 ,@jacobb42 updated the message and release notes

[mattbriggs]

@bganapa you have specified 1810. I think we are just now at the 1809 release. (https://docs.microsoft.com/en-us/azure/azure-stack/azure-stack-update-1809) Do you mean 1810 or 1809? If you mean 1809, then can you update. If it is for 1810 I'll touch base directy so I understand better how we should make the change and schedule a change.

[deathly809]

@mattbriggs The Test-AzureStack feature we mention won't be available until 1810.

[bganapa]

@mattbriggs Q raises another issue that there is no 1810 update release for azurestack, we are merging with 1811.. the release note should mention 1811 instead of 1810

[mattbriggs]

#sign-off

[bganapa]

ps-sign https://azuresdkci.westus2.cloudapp.azure.com/view/PowerShell/job/ps-sign/1521/