Add relicense from zoobab

RELICENSE/zoobab.md

+# Permission to Relicense under MPLv2 or any other OSI approved license chosen by the current ZeroMQ BDFL
+
+This is a statement by Benjamin HENRION
+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 "zoobab", with
+commit author "Benjamin HENRION", are copyright of Benjamin HENRION .
+This document hereby grants the libzmq project team to relicense libzmq,
+including all past, present and future contributions of the author listed above.
+
+Benjamin HENRION (zoobab)
+Done in Brussels on the 2020/02/03