doc: update list of people in SECURITY.md

Update the list of people with access to:
- Private security reports against Node.js.
- Private security patches to Node.js.
The latter by running `ncu-team sync SECURITY.md`.
Signed-off-by: Richard Lau <richard.lau@ibm.com>
PR-URL: #64152
Refs: nodejs/Release#733
Refs: nodejs/TSC#1760
Reviewed-By: Beth Griggs <bethanyngriggs@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

Author: richardlau

SECURITY.md

@@ -532,6 +532,7 @@ In addition, these individuals have access:
 *[cjihrig](https://github.com/cjihrig)**Colin Ihrig**
 *[joesepi](https://github.com/joesepi) - **Joe Sepi**
 *[juanarbol](https://github.com/juanarbol)**Juan Jose Arboleda**
+*[sxa](https://github.com/sxa) - **Stewart X Addison**
 *[ulisesgascon](https://github.com/ulisesgascon)**Ulises Gascón**
 *[vdeturckheim](https://github.com/vdeturckheim) - **Vladimir de Turckheim**
 
@@ -546,6 +547,7 @@ the Node.js program on HackerOne.
 *[@anonrig](https://github.com/anonrig) - Yagiz Nizipli
 *[@bengl](https://github.com/bengl) - Bryan English
 *[@benjamingr](https://github.com/benjamingr) - Benjamin Gruenbaum
+*[@BethGriggs](https://github.com/BethGriggs) - Beth Griggs
 *[@bmeck](https://github.com/bmeck) - Bradley Farias
 *[@bnoordhuis](https://github.com/bnoordhuis) - Ben Noordhuis
 *[@BridgeAR](https://github.com/BridgeAR) - Ruben Bridgewater
@@ -568,6 +570,7 @@ the Node.js program on HackerOne.
 *[@ruyadorno](https://github.com/ruyadorno) - Ruy Adorno
 *[@santigimeno](https://github.com/santigimeno) - Santiago Gimeno
 *[@ShogunPanda](https://github.com/ShogunPanda) - Paolo Insogna
+*[@sxa](https://github.com/sxa) - Stewart X Addison
 *[@targos](https://github.com/targos) - Michaël Zasso
 *[@tniessen](https://github.com/tniessen) - Tobias Nießen
 *[@UlisesGascon](https://github.com/UlisesGascon) - Ulises Gascón