Update index.html

Author: OpenHelix-robot

index.html

@@ -48,8 +48,8 @@ <h1><strong>OpenHelix</strong>: A Short Survey, Empirical Analysis, and Open-Sou
     <div class="row text-center" style="margin-top: 20px;">
       <!-- PDF Link -->
       <span class="link-block">
-        <a href="https://openhelix-robot.github.io/" class="btn btn-custom" target="_blank">
-          <i class="fas fa-file-pdf"></i> Paper
+        <a href="https://github.com/OpenHelix-robot/awesome-dual-system-vla/" class="btn btn-custom" target="_blank">
+          <i class="fas fa-file-pdf"></i> Survey
         </a>
       </span>