Fix copyright notice in About page

agkyra/agkyra/gui/about.html

@@ -42,7 +42,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
             <p class="disclaimer">Developed and supported by the Okeanos/Synnefo development team of GRNET<br/><b>contact: okeanos-dev@grnet.gr</b></p>
 
             <h3 class="disclaimer">Copyright 2015 Greek Research and Technology Network<br/>Licensed under:</h3>
-            <embed class="box" src="COPYRIGHT" />
+            <embed class="box" src="COPYING" />
         </div>
         <footer class="footer js-footer">
             <nav class="row">