fix examples as a link leads to a malicious site (#347)

Sigmah is not a project anymore (merged with another project so not sure if it's still using gwt)

Co-authored-by: Colin Alworth <[email protected]>

Author: arjun-sa

src/main/markdown/examples.md

@@ -165,16 +165,6 @@ was built using GWT. Use the free trial to see it in action.</div>
   </div>
 </div>
 
-<div class="project">
-  <div class="screenshot">
-    <a href="http://www.sigmah.org" target="_blank"><img src="images/sigmah-dashboard-gwtThumbNail.jpg" alt="Sigmah"/></a>
-  </div>
-  <div class="info">
-    <div class="name"><a href="http://www.sigmah.org" target="_blank">Sigmah</a></div>
-    <div class="snippet">Sigmah is open source software for the shared management of international aid projects. &ndash; The software is simple, flexible and intuitive and allows each organisation to organize its own work methods, and thereby improve the quality of its programmers. &ndash; Sigmah is a big web application built using GWT, and providing a full-web <strong>offline mode</strong> working in production environment with Mozilla Firefox.</div>
-  </div>
-</div>
-
 <div class="project">
   <div class="screenshot">
     <a href="https://www.cloudorado.com" target="_blank"><img src="images/cloudorado.png" alt="cloudorado"/></a>