[gnome-chess] help: Fix gui type

[Andre Klapper <aklapper src gnome org>]

commit b3798ce1e1a7fe8125577d079a77940646c88a26
Author: Andre Klapper <a9016009 gmx de>
Date:   Wed Sep 5 10:48:02 2018 +0200

    help: Fix gui type

 help/C/chess-engines.page | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/help/C/chess-engines.page b/help/C/chess-engines.page
index 26d3545..eddc04a 100644
--- a/help/C/chess-engines.page
+++ b/help/C/chess-engines.page
@@ -26,7 +26,7 @@
     </item>
     <item>
       <p>Under <gui>Opposing player</gui>, choose
-      <gui style="radiobutton">Human</gui> for both players if want to play
+      <gui style="menuitem">Human</gui> for both players if want to play
       with a friend or family member.</p>
       <p>Alternatively, choose a different chess engine. The list depends on
       the chess engines installed on your system.