fix voxel link

Author: faparicior

index.html

@@ -1403,7 +1403,7 @@ <h1 class="section-title">
                             </a>
                         </div>
                         <div>
-                            <a class="sponsor" href="https://www.voxel.com/" target="_blank">
+                            <a class="sponsor" href="https://www.voxelgroup.net/" target="_blank">
                                 <img src="assets/img/sponsors/voxel.png" alt="Voxel" />
                             </a>
                         </div>