doc: PG 13 relnotes: fix FETCH FIRST ... WITH TIES xreflabel

Reported-by: Erwin Brandstetter

Discussion: https://postgr.es/m/CAGHENJ4X626ZfYhondXSP4sQgC5zDtsp_LNg1QaD+U7vfgYXQQ@mail.gmail.com

Backpatch-through: head

doc/src/sgml/release-13.sgml

@@ -1376,7 +1376,7 @@ Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
 -->
 
       <para>
-       Allow <link linkend="sql-fetch"><command>FETCH FIRST</command></link>
+       Allow <link linkend="sql-select"><command>FETCH FIRST</command></link>
        to use <literal>WITH TIES</literal> to return any additional rows
        that match the last result row (Surafel Temesgen)
       </para>