Add Echo Unify Systems to showcase

Author: knolleary

index.html

@@ -120,6 +120,7 @@ <h4>In the cloud</h4>
         <div class="content">
             <h3>Who's using Node-RED?</h3>
             <ul id="user-list">
+                <li><a href="https://www.echounify.com/"><img src="users/echo-unify-systems.png"/></a></li>
                 <li><a href="https://www.overview.ai/"><img src="users/overviewai.jpg"/></a></li>
                 <li><a href="https://www.ubos.tech/"><img src="users/ubos.jpg"/></a></li>
                 <li><a href="https://www.bitpool.com/"><img src="users/bitpool.png"/></a></li>