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.

2004/jdalbec/README.md

@@ -170,3 +170,12 @@ By using ternary operators to avoid "else"
 By using the Sb function to create subbuffers from either end
 By naming everything after chemical elements or pairs of elements
 Because it says so in the source. ;)
+
+## 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/