Adding firewall prerequisite information

[johnmart82]

While trying to follow the example in this page I was getting GatewayTimeout errors. After updating the firewall to allow Azure services the examples work fine. This is important information to the success of the reader executing the example code. As this is essential information required for user success it has been highlighted as Important.

Description

After trying to get the example code to work I tested with Allow azure services option enabled on the firewall. As this is important for the readers success when testing I have added it as Important information.

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
• For public API changes to cmdlets:
  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
  • the markdown help files have been regenerated using the commands listed here

[ghost]

Thank you for your contribution johnmart82! We will review the pull request and get back to you soon.

[isra-fel]

Thanks for your contribution again @johnmart82 !
@brandong-ms @xaliciayang could you review the change to the doc of New-AzSqlDatabaseExport, or suggest someone to review please? Thank you

[isra-fel]

@mikefrobbins Hello Mike could you help Sql team to review this PR? Thanks in advance 😀

[msJinLei]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[mikefrobbins]

LGTM

[isra-fel]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[isra-fel]

/azp run azure-powershell - windows-powershell

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).