add relicensing grant

RELICENSE/FrancescoMontorsi.md

+# Permission to Relicense under MPLv2 or any other OSI approved license chosen by the current ZeroMQ BDFL
+
+This is a statement by Francesco Montorsi that grants permission to relicense
+its copyrights in the libzmq C++ library (ZeroMQ) under the Mozilla Public
+License v2 (MPLv2) or any other Open Source Initiative approved license
+chosen by the current ZeroMQ BDFL (Benevolent Dictator for Life).
+
+A portion of the commits made by the Github handle "f18m", with
+commit author "Francesco Montorsi <francesco.montorsi@gmail.com>", are copyright
+of Francesco Montorsi.  This document hereby grants the libzmq project
+team to relicense libzmq, including all past, present and future
+contributions of the author listed above.
+
+Francesco Montorsi
+2018/09/14