docs: replace highlight.js demo url (#10463)

Author: baptisthecht

docs/usage/configuration.md

@@ -222,7 +222,7 @@ Parameter name | Docker variable | Description
         <td><em>Unavailable</em></td>
         <td><code>String=["agate"*, "arta", "monokai", "nord", "obsidian",
             "tomorrow-night", "idea"]</code>. <a
-                href="https://highlightjs.org/static/demo/" rel="nofollow">Highlight.js</a>
+                href="https://highlightjs.org/demo/" rel="nofollow">Highlight.js</a>
             syntax coloring theme to use. (Only these 7 styles are available.)
         </td>
     </tr>