Redict discussions to Mathics-core discussions

Author: rocky

index.html

@@ -229,9 +229,8 @@ <h2 id="doc">Documentation</h2>
         <h2>Support</h2>
         <div class="inner align-left">
           <p>
-            Use the
-            <a href="https://groups.google.com/forum/#!forum/mathics-users">
-            mathics-users</a> mailing list or <a href="https://groups.google.com/forum/#!forum/mathics-users"> slack channel </a> for discussions regarding using Mathics.
+            Use <a href="https://github.com/Mathics3/mathics-core/discussions">
+            Mathics-core discussions </a>.
           </p>
 
           <ul>