This is how index.html should look like. The change consists of two things.

A bullet is added under preview features:
<li><a href="primitive-types-in-patterns-instanceof-switch-jls.html">Primitive Types in Patterns, <code>instanceof</code>, and <code>switch</code></a></li>
A file is renamed: from instanceof-jls.html to primitive-types-in-patterns-instanceof-switch-jls.html

Essentially the result should be as in JDK 24 EA (notice the sub-bullet "Primitive Types in Patterns, instanceof, and switch") but for JDK 23 EA (with JDK 23 labels in headers, this should be already the case I think).

https://download.java.net/java/early_access/jdk24/docs/specs/