rn-138: add Štěpán Němec among the helpers

Author: chriscool

rev_news/drafts/edition-138.md

@@ -562,4 +562,4 @@ Christian Couder &lt;<christian.couder@gmail.com>&gt;,
 Jakub Narębski &lt;<jnareb@gmail.com>&gt;,
 Markus Jansen &lt;<mja@jansen-preisler.de>&gt; and
 Kaartic Sivaraam &lt;<kaartic.sivaraam@gmail.com>&gt;
-with help from Simone Arpe and Tuomas Ahola.
+with help from Simone Arpe, Štěpán Němec and Tuomas Ahola.