add reference

Author: Deland-Han

support/windows-server/active-directory/failure-when-you-use-an-existing-computer-account-to-join-a-domain.md

@@ -103,3 +103,7 @@ To fix the issue, follow these steps:
 
 > [!WARNING]
 > Don't use the **NetJoinLegacyAccountReuse** registry workaround anymore in a fully patched environment. Support for the **NetJoinLegacyAccountReuse** registry key was removed by the August 13, 2024 Windows Update. The hardening behavior persists regardless of that registry key setting. Use steps 1 - 4 in this section.
+
+## Reference
+
+For more information about domain join hardening changes, see [KB5020276—Netjoin: Domain join hardening changes](https://support.microsoft.com/topic/kb5020276-netjoin-domain-join-hardening-changes-2b65a0f3-1f4c-42ef-ac0f-1caaf421baf8)