Update index.html

Author: gcherchi

index.html

@@ -280,7 +280,7 @@ <h3>Download links:</h3>
             </p>
 
             <p class="info">
-                <h3>Try VOLMAP Viewer now!</h3>
+                <h3><a href="https://volmap.github.io/viewer/" target="_blank">Try VOLMAP Viewer now!</a></h3>
             </p>
 
             <a href="https://volmap.github.io/viewer/" target="_blank">