doc: add Bethany to TSC

Refs: nodejs/TSC#718

PR-URL: #29546
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

README.md

@@ -154,6 +154,8 @@ For information about the governance of the Node.js project, see
 **Anna Henningsen** <anna@addaleax.net> (she/her)
 * [apapirovski](https://github.com/apapirovski) -
 **Anatoli Papirovski** <apapirovski@mac.com> (he/him)
+* [BethGriggs](https://github.com/BethGriggs) -
+**Beth Griggs** <Bethany.Griggs@uk.ibm.com> (she/her)
 * [ChALkeR](https://github.com/ChALkeR) -
 **Сковорода Никита Андреевич** <chalkerx@gmail.com> (he/him)
 * [cjihrig](https://github.com/cjihrig) -