doc: piscisaureus has stepped-down from the CTC

piscisaureus has voluntarily stepped-down from the CTC

PR-URL: https://github.com/nodejs/node/pull/7969


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>