Use CC BY instead of CC BY-SA

Author: trossi

COPYING

@@ -1,7 +1,6 @@
 All material Copyright (c) CSC - IT Center for Science Ltd. <www.csc.fi> unless otherwise noted.
 
-All text and image material licensed under Creative Commons BY-SA 4.0 unless
-otherwise noted. 
+All text and image material licensed under Creative Commons BY 4.0 unless otherwise noted.
 
 All code samples licensed under MIT license unless otherwise noted.