docs: credit kenney assets

Note the Car Kit, City Kit Roads, and Furniture Kit sources (CC0)
and add Kenney to the greetings scroller.

CREDITS.md

@@ -7,3 +7,12 @@
 - Source: [The Mod Archive, module id 67104](https://modarchive.org/index.php?request=view_by_moduleid&query=67104)
 - License: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/)
 - Used unmodified.
+
+## 3D models
+
+Low-poly models by [Kenney](https://kenney.nl/), from the **Car Kit**,
+**City Kit: Roads**, and **Furniture Kit** asset packs.
+
+- License: [CC0](https://creativecommons.org/publicdomain/zero/1.0/)
+  (public domain, no attribution required — credited here anyway).
+- Used as shipped, no retinting.

src/content/greetings.ts

@@ -6,6 +6,7 @@ export const GREETINGS = [
   'MLX',
   'KXKM',
   'Amiga forever',
+  'Kenney',
 ]
 
 export const SCROLLER_TEXT =