Fix setcookie() documentation for invalid options in PHP 8.0+ (#5104)

And move it to the usual dedicated Errors/Exception section

Co-authored-by: Gina Peter Banyard <girgias@php.net>

reference/network/functions/setcookie.xml

@@ -158,8 +158,9 @@
        An associative <type>array</type> which may have any of the keys
        <literal>expires</literal>, <literal>path</literal>, <literal>domain</literal>,
        <literal>secure</literal>, <literal>httponly</literal> and <literal>samesite</literal>.
-       If any other key is present an error of level <constant>E_WARNING</constant>
-       is generated. The values have the same meaning as described for the
+      </simpara>
+      <simpara>
+       The values have the same meaning as described for the
        parameters with the same name. The value of the <literal>samesite</literal>
        element should be either <literal>None</literal>, <literal>Lax</literal>
        or <literal>Strict</literal>.
@@ -168,6 +169,7 @@
        <literal>samesite</literal> element is omitted, no SameSite cookie
        attribute is set.
       </simpara>
+
       <note>
        <simpara>
         To set a cookie that includes attributes that aren't among the keys listed,
@@ -197,6 +199,25 @@
   </simpara>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   If the <parameter>options</parameter> array contains unsupported keys:
+  </simpara>
+  <itemizedlist>
+   <listitem>
+    <simpara>
+     Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was generated.
+    </simpara>
+   </listitem>
+   <listitem>
+    <simpara>
+     As of PHP 8.0.0, a <exceptionname>ValueError</exceptionname> is thrown.
+    </simpara>
+   </listitem>
+  </itemizedlist>
+ </refsect1>
+
  <refsect1 role="changelog">
   &reftitle.changelog;
   <informaltable>
@@ -223,6 +244,14 @@
        SameSite cookie attribute.
       </entry>
      </row>
+     <row>
+      <entry>8.0.0</entry>
+      <entry>
+       Passing unsupported keys now throws a <exceptionname>ValueError</exceptionname>
+       instead of emitting an <constant>E_WARNING</constant>.
+      </entry>
+     </row>
+
     </tbody>
    </tgroup>
   </informaltable>