Fix broken link

index.html

@@ -667,7 +667,7 @@ <h3 id="Categories">&sect;1.2. Categories of data</h3>
                     <td align="center">no</td>
                     </tr>
                     <tr>
-                    <td>Materials classes (various groups of terms: <i>i.e.</i> mineral names, periodic groups, physical classes, element count keywords <i>etc.</i>, see <a href="#L1">examples</a>)</td>
+                    <td>Materials classes (various groups of terms: <i>i.e.</i> mineral names, periodic groups, physical classes, element count keywords <i>etc.</i>, see <a href="https://tutorial.mpds.io/#Classes">examples</a>)</td>
                     <td><span class="t">classes</span></td>
                     <td><span class="t">perovskite</span>, <span class="t">quaternary</span></td>
                     <td align="center">no</td>