improve the footer of HTML files

We improve the `inc/footer.default.html` file to make
the _Copyright and CC BY-SA 4.0 License_ clear.

We add `license.md` and generate `license.html` (via `make
gen_top_html`) so that key features and terms of the _Copyright and
CC BY-SA 4.0 License_ are accessible.

Add CC BY-SA 4.0 license images into the `png/` directory.

FYI: We use the license to allow the open use of IOCCC entry code,
and at the same time, we help ensure that those working on the IOCCC
have proper Attribution including, of course, the IOCCC winners
themselves!  The _Copyright and CC BY-SA 4.0 License_ help ensure
that everyone may enjoy the IOCCC.

Added '#copyright' to all generated HTML pages so that the
_Copyright and CC BY-SA 4.0 License_ may be reached.

Changed `bin/gen-top-html.sh` VERSION from "1.2.2 2024-03-26"
to "1.2.3 2024-04-12".

Fix `bin/gen-sitemap.sh` to remove requirement of `ioccc.tar.bz2`.

Changed `bin/gen-sitemap.sh` VERSION from "1.3.4 2024-03-27"
to "1.3.5 2024-04-13".

Perform `make www sitemap` to perform the above.

We also give a _hint_ as to the next project.

TODO: Complete that next project we are _hinting_ at.

TODO: Review the work being done by a web designer to see
      how their work might be incorporated into the web site.

faq.html

@@ -203,6 +203,7 @@ other inconsistencies with the original entry?</a></li>
 <li><a href="#faq6_8">6.8 - What is the purpose of the .top, .year and .path files?</a></li>
 <li><a href="#faq6_9">6.9 - What is the current meaning of the IOCCC terms Author, Entry, and Submission?</a></li>
 <li><a href="#faq6_10">6.10 - How does someone make a change to a file and submit that change as a GitHub pull request?</a></li>
+<li><a href="#faq6_11">6.11 - Am I allowed to use IOCCC content?</a></li>
 </ul>
 <h1 id="the-ioccc-faq">The IOCCC FAQ</h1>
 <h2 id="section-0-submitting-entries-to-a-new-ioccc"><a name="faq0"></a>Section 0: Submitting entries to a new IOCCC</h2>
@@ -1758,6 +1759,10 @@ something like that.</p>
 we request that you ask the <a href="judges.html">IOCCC judges</a> first.</p>
 <p>Please send your request using the instructions on the <a href="/contact.html">contacting
 the IOCCC Judges</a> page.</p>
+<p>Please note that the content of the IOCCC is <a href="#copyright">Copyrighted and is under
+the CC BY-SA 4.0 License</a>.</p>
+<p>See <a href="#license">FAQ 6.11</a> for additional information on the
+<a href="license.html">Copyright and CC BY-SA 4.0 License</a>.</p>
 <h3 id="faq-6.4-why-do-you-sometimes-use-the-first-person-plural"><a name="faq6_4"></a>FAQ 6.4: Why do you sometimes use the first person plural?</h3>
 <p>As a precedent for <a href="https://en.wikipedia.org/wiki/Nosism">first person
 plural</a>, we may sight <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.35.1442">Two-,
@@ -2319,6 +2324,29 @@ has the merge. To do this from the command line, assuming the fork in the above
 example, you would type:</p>
 <pre class="&lt;!---sh--&gt;"><code>    git checkout master &amp;&amp; git pull https://github.com/ioccc-src/temp-test-ioccc.git master &amp;&amp; git push origin master</code></pre>
 <p>This will merge your pull request to your fork.</p>
+<h3 id="faq-6.11-am-i-allowed-to-use-ioccc-content"><a name="faq6_11"></a><a name="license"></a>FAQ 6.11: Am I allowed to use IOCCC content?</h3>
+<p><strong>Disclaimer</strong>: This FAQ is <strong>not a license</strong>, has <strong>no legal
+value</strong>, and only highlights some of the key features and terms of
+the actual <a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">CC BY-SA 4.0
+license</a>.</p>
+<p>The content of the IOCCC is <a href="#copyright">Copyrighted and is under the CC BY-SA 4.0 License</a>.</p>
+<p>As long as you abide by the terms of the <a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1">CC BY-SA 4.0
+License</a>
+you may copy and redistribute the material in any medium or format
+for any purpose, even commercially.</p>
+<p>As long as you abide by the terms of the <a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1">CC BY-SA 4.0
+License</a>
+you may remix, transform, and build upon the material for any
+purpose, even commercially.</p>
+<p>This FAQ is an incomplete summary of how you may use IOCCC content.
+You should review the <a href="license.html">highlights of some of the key features and terms</a>
+and this may help clarify some aspects of the
+<a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1">CC BY-SA 4.0 License</a>.</p>
+<p>The <a href="#copyright">Copyright and CC BY-SA 4.0 License</a> applies to all
+IOCCC content. We use this to help ensure that we can all
+enjoy hat those working on the IOCCC have proper Attribution
+including, of course, the IOCCC winners themselves! It is designed
+to help ensure that everyone may enjoy the IOCCC.</p>
 <!--
 
     Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
@@ -2364,14 +2392,30 @@ example, you would type:</p>
 -->
 
 <div class="footer">
-  <h2>Copyright and CC BY-SA 4.0 License</h2>
-  <p>This file and web page is:</p>
-  <blockquote><b>Copyright &copy; 1984-2024 by Landon Curt Noll. All Rights Reserved.</b></blockquote>
-  <p>You are free to share and adapt this file under the terms of this license:</p>
-  <blockquote><b>Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)</b></blockquote>
-  <p>For more information, see:</p>
-  <blockquote><a
-    href="https://creativecommons.org/licenses/by-sa/4.0/">https://creativecommons.org/licenses/by-sa/4.0/</a></blockquote>
+  <h2><a name="copyright"></a>Copyright and CC BY-SA 4.0 License</h2>
+  <p>All IOCCC content including this file and web page are:</p>
+  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Copyright &copy; 1984-2024 by Landon Curt Noll. <a href="https://creativecommons.org/faq/#what-does-some-rights-reserved-mean">Some Rights Reserved</a>.</b>
+  <p>This work is licensed by Landon Curt Noll under:</p>
+  <p xmlns:cc="http://creativecommons.org/ns#" ><b><a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
+  target="_blank" rel="license noopener noreferrer" style="display:inline-block;">&nbsp;&nbsp;&nbsp;&nbsp;CC BY-SA 4.0
+  <img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
+  src=".//svg/cc.svg"
+  alt="cc inside circle symbol">
+  <img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
+  src=".//svg/by.svg"
+  alt="person inside circle symbol">
+  <img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
+  src=".//svg/sa.svg"
+  alt="arrow looping back on itself inside circle symbol">
+  </a></b></p>
+  <p>The <b>CC BY-SA 4.0 LEGAL CODE</b> for this license is found under:</p>
+  <p>&nbsp;&nbsp;&nbsp;<b><a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">
+  https://creativecommons.org/licenses/by-sa/4.0/legalcode.en</a></b></p>
+  <p>You should <b>carefully review</b> all of the terms and conditions of the
+  <a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">actual license</a>
+  before using the licensed material.</p>
+  <p>You may wish to review the <b><a href="./license.html">highlights of some of the key
+  features and terms</a></b> of the <a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">actual license</a>.</p>
   <h2>Coda</h2>
   <p><a href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fioccc-src.github.io%2Ftemp-test-ioccc%2Flocation.html">Nu HTML check this web page</a></p>
   <p><a href="#top">Jump to top</a> <a href="#content">Jump to Content</a> <a href="#inventory">Jump to Inventory</a></p>