update screenshot and copyright notice

COPYING

@@ -30,3 +30,17 @@ Note that the skin is:
 - and created for WikiSkripta, a medical wiki project:
 
 	https://www.wikiskripta.eu
+
+Also note that the following file is attached to the skin:
+
+- the screenshot (assets/write.png) of Qiuwen Baike, A collaborative open-source free encyclopedia:
+
+	https://www.qiuwenbaike.cn
+
+- and the image of the tower in Yingze Park, Taiyuan, Shanxi, China:
+
+    https://www.qiuwenbaike.cn/wiki/File:%E5%A4%AA%E5%8E%9F%E5%B8%82%E8%BF%8E%E6%B3%BD%E5%85%AC%E5%9B%AD%E5%A1%94%E6%A5%BC.jpg
+
+  are all provided under CC BY-SA 4.0:
+
+    https://creativecommons.org/licenses/by-sa/4.0/