Add RELICENSE grant for mdionisio

Signed-off-by: Michele Dionisio <michele.dionisio@gmail.com>

RELICENSE/mdionisio.md

+# Permission to Relicense under MPLv2
+
+This is a statement by Thomas M. DuBuisson
+that grants permission to relicense its copyrights in the libzmq C++
+library (ZeroMQ) under the Mozilla Public License v2 (MPLv2).
+
+A portion of the commits made by the Github handle "mdionisio", with
+commit author "Michele Dionisio", are copyright of Michele Dionisio.
+This document hereby grants the libzmq project team to relicense libzmq,
+including all past, present and future contributions of the author listed above.
+
+Michele Dionisio
+2019/07/09