put all README.md files under CC BY-SA 4.0 License

This will make is easier for others to share README.md
files while requiring them to attribute the file
when using it.

1996/eldby/README.md

@@ -28,3 +28,12 @@ in a very small chunk of code.
 This program shows flying spheres. The program eats CPU on lesser
 equipped systems. The program will run until termination. Terminal 
 must be vt100 or better with 80 columns and 24 rows or more.
+
+## Copyright and CC BY-SA 4.0 License:
+
+This file is Copyright (c) 2023 by Landon Curt Noll.  All Rights Reserved.
+You are free to share and adapt this file under the terms this license:
+
+    Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
+
+For more information, see: https://creativecommons.org/licenses/by-sa/4.0/