docs: add Notification section to SECURITY.md (#24926)

adds a new section pointing to a relevant doc in Governance that defines how we notify end-users of security issues.

SECURITY.md

@@ -8,5 +8,9 @@ The Electron team will send a response indicating the next steps in handling you
 
 Report security bugs in third-party modules to the person or team maintaining the module. You can also report a vulnerability through the [Node Security Project](https://nodesecurity.io/report).
 
+## The Electron Security Notification Process
+
+For context on Electron's security notification process, please see the [Notifications](https://github.com/electron/governance/blob/master/wg-security/membership-and-notifications.md#notifications) section of the Security WG's [Membership and Notifications](https://github.com/electron/governance/blob/master/wg-security/membership-and-notifications.md) Governance document.
+
 ## Learning More About Security
 To learn more about securing an Electron application, please see the [security tutorial](docs/tutorial/security.md).