Fix doc build, broken by 13e0fa7.

Reported-by: Peter Geoghegan

Author: jeff-davis

doc/src/sgml/release-13.sgml

@@ -626,7 +626,7 @@ Author: Jeff Davis <jdavis@postgresql.org>
        <para>
         Previously, hash aggregation was avoided if it was expected to use
         more than <xref linkend="guc-work-mem"/> memory.  This is controlled
-        by <xref linkend="guc-enable-hashagg-disk"/>.
+        by <xref linkend="guc-hashagg-avoid-disk-plan"/>.
        </para>
       </listitem>
 
@@ -641,12 +641,6 @@ Author: Jeff Davis <jdavis@postgresql.org>
         use hash aggregation with disk storage for large grouping set results
         (Jeff Davis)
        </para>
-
-       <para>
-        Previously, hash aggregation was avoided if it was expected to use
-        more than <xref linkend="guc-work-mem"/> memory.  This is controlled
-        by <xref linkend="guc-enable-groupingsets-hash-disk"/>.
-       </para>
       </listitem>
 
       <listitem>