doc PG 17 relnotes: add Heikki Linnakangas to vacuum item

Reported-by: Melanie Plageman

Discussion: https://postgr.es/m/CAAKRu_YYR5MXY-xuCpr7DKKugCExTSjRy9Ax8c-z7LKa8dDfwg@mail.gmail.com

Author: Melanie Plageman

Backpatch-through: master

Author: bmomjian

doc/src/sgml/release-17.sgml

@@ -498,7 +498,7 @@ Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
 
 <listitem>
 <para>
-Allow vacuum to more efficiently remove and freeze tuples (Melanie Plageman)
+Allow vacuum to more efficiently remove and freeze tuples (Melanie Plageman, Heikki Linnakangas)
 </para>
 
 <para>