readme udpate (#211)

README.md

@@ -3,6 +3,12 @@
 [![Build Status](https://travis-ci.com/ZenGo-X/multi-party-ecdsa.svg?branch=master)](https://travis-ci.com/zengo-x/multi-party-ecdsa)
 [![License: GPL v3](https://img.shields.io/badge/License-GPL%20v3-blue.svg)](https://www.gnu.org/licenses/gpl-3.0)
 
+## IMPORTANT NOTE
+This repository is no longer maintained. Most specifically, Zengo will not provide any security updates or hotfixes (should an issue arise).
+This library was originally created to enable users to experiment with MPC and TSS functionality using different protocols, including such that are not used in production by Zengo wallet.
+Zengo wallet’s production MPC code can be found in https://github.com/ZenGo-X/gotham-city/pull/64
+
+## Introduction
 This project is a Rust implementation of {t,n}-threshold ECDSA (elliptic curve digital signature algorithm).
 
 Threshold ECDSA includes two protocols: