[quadrapassel] Updated the text to show this new way to restart the game quickly

[John Ward <jward src gnome org>]

commit ad9845a22ad5187d59bfc103dca485c3d0fe1795
Author: John Ward <john johnward net>
Date:   Wed Sep 30 12:14:38 2020 +0100

    Updated the text to show this new way to restart the game quickly

 help/C/playgame.page | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/help/C/playgame.page b/help/C/playgame.page
index dab74c9..6de12ac 100644
--- a/help/C/playgame.page
+++ b/help/C/playgame.page
@@ -30,6 +30,7 @@
   <item><p>The <key>&#8592;</key> and <key>&#8594;</key> keys move the blocks across the screen.</p></item>
   <item><p>The <key>&#8593;</key> key rotates the block. The rotation (which is counterclockwise by default) 
can be changed in the <link xref="preferences">Preferences</link>.</p></item>
   <item><p>The <key>SPACEBAR</key> and <key>&#8595;</key> key increase the speed of the drop. The 
<key>SPACEBAR</key> causes a hard-drop (instant move to the bottom). The <key>&#8595;</key> key causes a 
soft-drop (temporary increase in speed while the key is held down).</p></item>
+  <item><p>The <key>Enter</key> will restart the game quickly once it is game over.</p></item>
 </list>
 </section>