doc: add Gireesh to TSC

TSC voted in Gireesh today. Add him to the TSC list in the README.

Closes: nodejs#26186

PR-URL: nodejs#26657
Fixes: nodejs#26186
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>

Author: Trott

README.md

@@ -184,6 +184,8 @@ For information about the governance of the Node.js project, see
 **Jeremiah Senkpiel** <fishrock123@rocketmail.com>
 * [gabrielschulhof](https://github.com/gabrielschulhof) -
 **Gabriel Schulhof** <gabriel.schulhof@intel.com>
+* [gireeshpunathil](https://github.com/gireeshpunathil) -
+**Gireesh Punathil** <gpunathi@in.ibm.com> (he/him)
 * [joyeecheung](https://github.com/joyeecheung) -
 **Joyee Cheung** <joyeec9h3@gmail.com> (she/her)
 * [mcollina](https://github.com/mcollina) -