[gnome-backgrounds] mention existence of wallpaper assets

[Jakub Steiner <jimmac src gnome org>]

commit 634b57dd1aaed740824cba7176591ea1bee5deef
Author: Jakub Steiner <jimmac gmail com>
Date:   Mon May 16 13:04:49 2022 +0200

    mention existence of wallpaper assets
    
    Make it easy for people to create derivative works.
    
    Fixes https://gitlab.gnome.org/GNOME/gnome-backgrounds/-/issues/31

 README.md | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/README.md b/README.md
index be08dbf..6e0783c 100644
--- a/README.md
+++ b/README.md
@@ -40,6 +40,9 @@ Many photographic sources look great as a thumbnail or scaled down, but at 1:1 a
 
 Images should look decent even on lower quality displays. Techniques such as dithering should be used for 
elements with low contrast areas that would otherwise be prone for color banding.
 
+## Background "source"
+To easily create derivative works, the [wallpaper-assets 
repo](https://gitlab.gnome.org/Teams/Design/wallpaper-assets) contains most of the abstract wallpapers as 
Blender project files.
+
 ## License
 
 CCBYSA / Public Domain / CC0 is preferred. Authorship does need to be sourced, all attribution goes to the 
AUTHORS file.