adding arxiv link

Author: quentinll

publications/simple-contact-solver/index.html

@@ -106,7 +106,7 @@ <h1 class="title is-1 publication-title">From Compliant to Rigid Contact Simulat
                 </a>
               </span>
               <span class="link-block">
-                <a href="placeholder"
+                <a href="https://arxiv.org/abs/2405.17020"
                    class="external-link button is-normal is-rounded is-dark">
                   <span class="icon">
                       <i class="ai ai-arxiv"></i>