doc: add RafaelGSS as steward July 25

PR-URL: nodejs#59078
Reviewed-By: Richard Lau <richard.lau@ibm.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>

Author: RafaelGSS

doc/contributing/security-release-process.md

@@ -37,6 +37,7 @@ The current security stewards are documented in the main Node.js
 | NodeSource   | Rafael          | 2024-Jul-08  |
 | NodeSource   | Rafael          | 2025-Jan-21  |
 | NodeSource   | Rafael          | 2025-May-14  |
+| NodeSource   | Rafael          | 2025-July-15 |
 | Datadog      | Bryan           |              |
 | IBM          | Joe             |              |
 | Platformatic | Matteo          |              |