doc PG 17 relnotes: add FETCH_COUNT item

Reported-by: Daniel Verite

Discussion: https://postgr.es/m/82569de4-9b2a-4311-beb2-81d5418491ec@manitou-mail.org

Backpatch-through: master

doc/src/sgml/release-17.sgml

@@ -1893,8 +1893,6 @@ This is similar to PQpipelineSync() but it does not flush to the server unless t
 <!--
 Author: Tom Lane <tgl@sss.pgh.pa.us>
 2024-04-06 [4643a2b26] Support retrieval of results in chunks with libpq.
-Author: Tom Lane <tgl@sss.pgh.pa.us>
-2024-04-06 [90f517821] Re-implement psql's FETCH_COUNT feature atop libpq's chu
 -->
 
 <listitem>
@@ -1937,6 +1935,17 @@ This is enabled with the client-side option sslnegotation=direct, requires ALPN,
 
      <itemizedlist>
 
+<!--
+Author: Tom Lane <tgl@sss.pgh.pa.us>
+2024-04-06 [90f517821] Re-implement psql's FETCH_COUNT feature atop libpq's chu
+-->
+
+<listitem>
+<para>
+Allow FETCH_COUNT to work with non-SELECT queries (Daniel Vérité)
+</para>
+</listitem>
+
 <!--
 Author: Tom Lane <tgl@sss.pgh.pa.us>
 2023-11-13 [d1379ebf4] Improve default and empty privilege outputs in psql.