Update file-name-transact-sql.md

[0x7FFFFFFFFFFFFFFF]

Add important information about the function.

[prmerger-automator]

@0x7FFFFFFFFFFFFFFF : Thanks for your contribution! The author(s) have been notified to review your proposed change.

[learn-build-service-prod]

Learn Build status updates of commit d8055a5:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/t-sql/functions/file-name-transact-sql.md	✅Succeeded

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[learn-build-service-prod]

Learn Build status updates of commit b828055:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/t-sql/functions/file-name-transact-sql.md	✅Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[Court72]

@markingmyname

Can you review the proposed changes?

When the changes are ready for publication, add a #sign-off comment to signal that the PR is ready for the review team to merge.

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

[rwestMSFT]

@Court72 You can sign this off at your convenience.

[Court72]

Due to the upcoming Ignite conference, all merging and publishing is on hold until the morning of 11/15.

This PR is ready for merge on 11/15.

#label: "event-triaged-to-10AM"
#label: "missed-content-complete"

[prmerger-automator]

PR 9485 has been merged from 0x7FFFFFFFFFFFFFFF:patch-38 to MicrosoftDocs:live by Court72.

@0x7FFFFFFFFFFFFFFF, @0x7, @markingmyname