improve Copyright and CC

The inc/footer.default.html now has a common Copyright and CC BY-SA
4.0 License section for all generated HTML files.

All markdown files have a similar Copyright and CC
at the bottom in the form of an HTML comment.

inc/README.md

@@ -12,3 +12,18 @@ by the web server or the browser.  Content of HTML files is
 processed by tools the [bin](../bin/index.html) directory.
 Processing can include substitution of strings of the form _%%CURDS%%_ with some command
 line supplied value by the tool in question.
+
+
+<!--
+
+    Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
+
+    You are free to share and adapt this file under the terms of 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/
+
+-->