Update expressroute-bfd.md to reflect IPv6 support

[NaotakaKawakami]

The article currently states that BFD is supported only for IPv4 on ExpressRoute. I believe this limitation has been removed, and BFD is now supported for both IPv4 and IPv6.
This update corrects the documentation to avoid misleading readers.

[prmerger-automator]

@NaotakaKawakami : 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 42bd33a:

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[Copilot]

Pull Request Overview

Updates documentation to remove outdated limitation statement about BFD IPv4-only support on ExpressRoute by commenting out the existing note, indicating that BFD now supports both IPv4 and IPv6.

• Commented out the IPv4-only limitation note in the BFD documentation

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[Copilot]

Using /* */ comment syntax in Markdown is incorrect and will be rendered as visible text. Either remove these lines entirely or use HTML comments <!-- --> if you need to preserve the content for reference.

Suggested change

	/*
	> [!NOTE]
	> BFD is only supported on IPv4 peering.
	>
	*/
	<!--
	> [!NOTE]
	> BFD is only supported on IPv4 peering.
	>
	-->

[ttorble]

@duongau

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"
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