note old Email, header formatting, improve copyright and license

For the top level and year level README.md, where email are found,
a note was added to the effect that email addresses found above are
for historical purposes only, and should not be used today.

Old references to asking for fixes, comments, when content was used,
and next contest links were replaced with a general reference to the FAQ.

Harmonized the Copyright and License and copyright dates.
Now using Creative Commons "CC BY-SA 4.0 DEED Attribution-ShareAlike 4.0
International".

The above Creative Commons will become the standard for the IOCCC.
Replaced old `png/by-sa-3.0-88x31.png` with a new ` png/by-sa.88x31.png` icon.
Updated the top level HTML files to use the license.

2018/README.md

@@ -1,11 +1,5 @@
 # 2018 marked the "The Twenty Fifth International Obfuscated C Code Contest"
 
-Copyright (C) 2018, Landon Curt Noll, Simon Cooper, and Leonid A.
-Broukhis. All Rights Reserved. Permission for personal, educational
-or non-profit use is granted provided this copyright and notice are
-included in its entirety and remains unaltered.  All other uses
-must receive prior permission from the contest judges.
-
 
 ## Standard IOCCC stuff
 
@@ -93,21 +87,15 @@ the idea was limited in scope.
 
 ## Final Comments
 
-Please feel free to send us comments and suggestions about the
-competition, this README or anything else that you would like to see in
-future contests.
+**IMPORTANT NOTE**: See [contact.html](/contact.html) for up to date contact details
+as well as details on how to provide fixes to any of the entries.
+See also [the IOCCC FAQ](/faq.html) for addition information on the IOCCC.
 
-If you use, distribute or publish these entries in some way, please drop
-us a line.  We enjoy seeing who, where and how the contest is used.
 
-If you have problems with any of the entries, AND YOU HAVE A FIX, please
-send us the fix (patch file or the entire changed file).
-
-For the latest information on how to contact the IOCCC Judges please visit
-
->	<https://www.ioccc.org/contact.html>
-
-For news of the next contest watch:
-
->	<https://www.ioccc.org/>
+# Copyright and License
 
+Copyright (C) 2018,2023, Landon Curt Noll and Leonid A. Broukhis. All Rights Reserved.
+This work is licensed under a [Creative Commons CC BY-SA 4.0 DEED Attribution-ShareAlike
+4.0 International](https://creativecommons.org/licenses/by-sa/4.0/) license.
+If you do use this work in some form, the [IOCCC judges](/judges.html) would appreciate
+(but does not require) if you were to [send us a note about your use](/contact.html).