[gbrainy] Remove reference in the help for 3rd party addons

[Jordi Mas <jmas src gnome org>]

commit 66c65b1d6ac00cbac0229674fe487a3afb0f0478
Author: Jordi Mas <jmas softcatala org>
Date:   Sat Sep 3 20:07:23 2022 +0200

    Remove reference in the help for 3rd party addons

 help/C/gameplay.page | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
---
diff --git a/help/C/gameplay.page b/help/C/gameplay.page
index c9ff87df..452d5a39 100644
--- a/help/C/gameplay.page
+++ b/help/C/gameplay.page
@@ -30,9 +30,7 @@
   <p>
     You can choose different difficulty levels making <app>gbrainy</app> 
     enjoyable for kids, adults or senior citizens. It also features a game history, 
-    personal records, tips and fullscreen mode support. <app>gbrainy</app> can also 
-    be <link href="https://wiki.gnome.org/Apps/gbrainy/Extending";>extended</link> easily 
-    with new games developed by third parties.
+    personal records, tips and fullscreen mode support.
   </p>
   <p>
     <app>gbrainy</app> relies heavily on the work of previous puzzle masters,