Add warning for Antimalware extension deployment

[rakena]

This is based on customer escalation (strategic customer Mediterranean Shipping) and requested by CXP ACE team.

[prmerger-automator]

@rakena : 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 cd2fdb0:

✅ Validation status: passed

File	Status	Preview URL	Details
articles/security/fundamentals/antimalware.md	✅Succeeded

For more details, please refer to the build report.

[v-regandowner]

Suggested change

	WARNING: Deploying or updating this extension will replace existing Defender AV settings, including exclusions.
	> [!WARNING]
	> Deploying or updating this extension will replace existing Defender AV settings, including exclusions.

[v-regandowner]

@msmbaldwin - 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

[Copilot]

Pull Request Overview

This PR adds a warning message to alert users that deploying or updating the Antimalware extension will replace existing Defender AV settings, including exclusions. This change was requested based on a customer escalation from a strategic customer.

Key Changes:

• Added a warning message in the Antimalware configuration documentation to inform users about the impact of deployment/updates on existing settings

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

The warning should be formatted using proper Markdown admonition syntax for better visibility. Consider using > [!WARNING] or similar syntax to make this stand out as a callout box rather than plain text.

Suggested change

	WARNING: Deploying or updating this extension will replace existing Defender AV settings, including exclusions.
	> [!WARNING]
	> Deploying or updating this extension will replace existing Defender AV settings, including exclusions.

[v-dirichards]

@msmbaldwin

Can you review this old PR and determine whether it needs to be closed or merged?

@MicrosoftDocs/public-repo-pr-review-team