Doc: update v15 release notes.

doc/src/sgml/release-15.sgml

@@ -3,7 +3,7 @@
 
   <formalpara>
    <title>Release date:</title>
-   <para>AS OF 2022-09-23</para>
+   <para>CURRENT AS OF 2022-10-03</para>
   </formalpara>
 
   <sect2>
@@ -936,24 +936,6 @@ Author: Tomas Vondra <tomas.vondra@postgresql.org>
        </para>
       </listitem>
 
-<!--
-Author: Tomas Vondra <tomas.vondra@postgresql.org>
-2022-03-31 [db0d67db2] Optimize order of GROUP BY keys
--->
-
-      <listitem>
-       <para>
-        Allow <link linkend="queries-group"><literal>GROUP
-        BY</literal></link> sorting to optimize column order (Dmitry
-        Dolgov, Teodor Sigaev, Tomas Vondra)
-       </para>
-
-       <para>
-        This optimization can be disabled using the server variable <link
-        linkend="guc-enable-groupby-reordering"><varname>enable_group_by_reordering</varname></link>.
-       </para>
-      </listitem>
-
 <!--
 Author: Tom Lane <tgl@sss.pgh.pa.us>
 2022-03-24 [0bd7af082] Invent recursive_worktable_factor GUC to replace hard-wi