Document output_add_rewrite_var() using url_rewriter.hosts bugfix (#4351)

Document the bugfix of php/php-src/pull/13294. This is a part of #3872.

Co-authored-by: haszi <[email protected]>

Author: haszi

reference/outcontrol/functions/output-add-rewrite-var.xml

@@ -45,6 +45,13 @@
     it cannot be started again.
    </simpara>
   </note>
+  <warning>
+   <simpara>
+    Prior to PHP 8.4.0, the hosts to be rewritten were set in
+    <link linkend="ini.session.trans-sid-hosts">session.trans_sid_hosts</link>
+    instead of <link linkend="ini.url-rewriter.hosts">url_rewriter.hosts</link>.
+   </simpara>
+  </warning>
  </refsect1>
 
  <refsect1 role="parameters">