Add security incident callback exclusion note to support docs (#61430)

Author: Kremlin

content/support/contacting-github-support/viewing-and-updating-support-tickets.md

@@ -65,6 +65,9 @@ You can also comment on tickets opened by someone else and associated with your
 
 If your account includes {% data variables.contact.premium_support %}, you can request a callback for urgent or high priority tickets. From the ticket, click **Request a callback from GitHub Support**.
 
+> [!NOTE]
+> Callbacks are not available for security-related tickets, such as incident notifications or account compromise investigations. These tickets are handled exclusively in writing through support tickets.
+
 ## Requesting an escalation
 
 You can request to escalate a ticket if it was opened at a lower priority but the issue has become more urgent{% ifversion ghec %} if your account includes {% data variables.contact.premium_support %}{% endif %}. From the ticket, click **Request an escalation**. For more information about requesting an escalation, see [AUTOTITLE](/support/learning-about-github-support/about-github-premium-support#assigning-a-priority-to-a-support-ticket).

content/support/learning-about-github-support/about-github-support.md

@@ -87,6 +87,8 @@ Email communication from GitHub Support will always be sent from either a `githu
 
 {% data reusables.support.scope-of-support %}
 
+For security-related matters, all communication is handled in writing through support tickets. This includes incident notifications, account compromise investigations, and credential exposure. Written communication ensures responses are reviewed, fully documented, and auditable. Callback and screen share requests cannot be accommodated for these tickets.
+
 {% ifversion ghec or fpt %}
 
 ## About GitHub status