Fix outdated link to model training essentia documentation

webserver/templates/datasets/accuracy.html

@@ -3,7 +3,7 @@
     <div id="accuracy-page">
 
     <h1 class="page-title">Accuracies and confusion matrices for default models</h1>
-      <p>Read more about the <a href="https://github.com/MTG/essentia/blob/master/FAQ.md#how-it-works">model training process on the essentia website</a>.</p>
+      <p>Read more about the <a href="https://essentia.upf.edu/machine_learning.html#how-it-works">model training process on the essentia website</a>.</p>
 
     <div class="table-of-contents">
       <h4>Table of Contents</h4>