doc: add kvakil to triagers

I am volunteering to be a triager. I'd like to become more involved,
help users with their issues, and eventually become a collaborator.

I've understood & agree to the code of conduct.

PR-URL: https://github.com/nodejs/node/pull/43996
Reviewed-By: Feng Yu <F3n67u@outlook.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Qingyu Deng <i@ayase-lab.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

README.md

@@ -658,6 +658,8 @@ maintaining the Node.js project.
   **Himadri Ganguly** <<himadri.tech@gmail.com>> (he/him)
 * [iam-frankqiu](https://github.com/iam-frankqiu) -
   **Frank Qiu** <<iam.frankqiu@gmail.com>> (he/him)
+* [kvakil](https://github.com/kvakil) -
+  **Keyhan Vakil** <<kvakil@sylph.kvakil.me>> (they/them)
 * [marsonya](https://github.com/marsonya) -
   **Akhil Marsonya** <<akhil.marsonya27@gmail.com>> (he/him)
 * [meixg](https://github.com/meixg) -