doc PG 17 relnotes: add two optimizer items

One is about subqueries becoming joins and the other is about optimizing
LIMIT by improving startup cost.

Reported-by: Andy Fan

Discussion: https://postgr.es/m/87h6f4ncc6.fsf@163.com

Reviewed-by: David Rowley

Backpatch-through: master

Author: bmomjian

doc/src/sgml/release-17.sgml

@@ -356,6 +356,28 @@ Improve optimization of range values when using containment operators <@ and
 </para>
 </listitem>
 
+<!--
+Author: Alexander Korotkov <akorotkov@postgresql.org>
+2024-02-15 [9f1337639] Pull up ANY-SUBLINK with the necessary lateral support.
+-->
+
+<listitem>
+<para>
+Allow correlated IN subqueries to be transformed into joins (Andy Fan, Tom Lane)
+</para>
+</listitem>
+
+<!--
+Author: David Rowley <drowley@postgresql.org>
+2023-10-05 [a8a968a82] Consider cheap startup paths in add_paths_to_append_rel
+-->
+
+<listitem>
+<para>
+Improve optimization of the LIMIT clause on partitioned tables, inheritance parents, and UNION ALL queries (Andy Fan, David Rowley)
+</para>
+</listitem>
+
 <!--
 Author: Tom Lane <tgl@sss.pgh.pa.us>
 2023-07-14 [e08d74ca1] Allow plan nodes with initPlans to be considered paralle