[gnome-chess] help: Add screenshot to play page

[Andre Klapper <aklapper src gnome org>]

commit 3fb56a0e361da321cce2b550f30e667fe95933bc
Author: Andre Klapper <a9016009 gmx de>
Date:   Wed Sep 5 10:52:48 2018 +0200

    help: Add screenshot to play page

 help/C/figures/game-3-28.png | Bin 0 -> 46356 bytes
 help/C/play.page             |   5 +++++
 2 files changed, 5 insertions(+)
---
diff --git a/help/C/figures/game-3-28.png b/help/C/figures/game-3-28.png
new file mode 100644
index 0000000..cb47ed5
Binary files /dev/null and b/help/C/figures/game-3-28.png differ
diff --git a/help/C/play.page b/help/C/play.page
index 6576309..b18fe92 100644
--- a/help/C/play.page
+++ b/help/C/play.page
@@ -16,4 +16,9 @@
 
   <title>How to Play</title>
 
+<media type="image" src="./figures/game-3-28.png" width="600">
+  <p>The main window in <app>GNOME Chess</app></p>
+</media>
+
+
 </page>