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.md

@@ -1,5 +1,6 @@
 # FAQ Table of Contents <!-- XXX - Change the references from _temp-test-ioccc_ to _winners_ when these fixes are merged. -->
 
+
 ## Section  0 - [Submitting entries to a new IOCCC](#faq0)
 - [0.0  - How may I submit to the IOCCC?](#faq0_0)
 - [0.1  - What types of entries have been over-submitted to the IOCCC?](#faq0_1)
@@ -8,12 +9,14 @@
 - [0.4  - What platform should I assume for my entry?](#faq0_4)
 - [0.5  - How may I comment or make a suggestion on IOCCC rules, guidelines and tools?](#faq0_5)
 
+
 ## Section  1 - [History of the IOCCC](#faq1)
 - [1.0  - How did the IOCCC get started?](#faq1_0)
 - [1.1  - Why are some years missing IOCCC entries?](#faq1_1)
 - [1.2  - What is the history of the IOCCC web site?](#faq1_2)
 - [1.3  - How has the IOCCC size limit rule changed over the years?](#faq1_3)
 
+
 ## Section  2 - [IOCCC Judging process](#faq2)
 - [2.0  - How many entries do the judges receive for a given IOCCC?](#faq2_0)
 - [2.1  - What should I put in the remarks.md file of my entry?](#faq2_1)
@@ -23,6 +26,7 @@
 - [2.5  - Why do some IOCCC entries receive the Grand Prize or Best of Show award?](#faq2_5)
 - [2.6  - How are IOCCC entries announced?](#faq2_6)
 
+
 ## Section  3 - [Compiling and running IOCCC entries](#faq3)
 - [3.0  - What Makefile rules are available to build or clean up IOCCC entries?](#faq3_0)
 - [3.1  - Why doesn't this IOCCC entry compile?](#faq3_1)
@@ -53,6 +57,7 @@
 other inconsistencies with the original entry?](#faq4_3)
 - [4.4  - What is the meaning of the file ending in .orig.c in IOCCC entries?](#faq4_4)
 
+
 ## Section  5 - [Helping the IOCCC](#faq5)
 - [5.0  - How may I help the IOCCC?](#faq5_0)
 - [5.1  - How do I report a bug in an IOCCC entry?](#faq5_1)
@@ -62,6 +67,7 @@ other inconsistencies with the original entry?](#faq4_3)
 - [5.5  - How may I correct or update IOCCC author information?](#faq5_5)
 - [5.6  - What should I do if I find a broken or wrong web link?](#faq5_6)
 
+
 ## Section  6 - [Miscellaneous IOCCC](#faq6)
 - [6.0  - How did an entry that breaks the size rule 2 win the IOCCC?](#faq6_0)
 - [6.1  - Is there a list of known bugs and (mis)features of IOCCC entries?](#faq6_1)
@@ -74,6 +80,7 @@ other inconsistencies with the original entry?](#faq4_3)
 - [6.8 -  What is the purpose of the .top, .year and .path files?](#faq6_8)
 - [6.9 -  What is the current meaning of the IOCCC terms Author, Entry, and Submission?](#faq6_9)
 - [6.10 - How does someone make a change to a file and submit that change as a GitHub pull request?](#faq6_10)
+- [6.11 - Am I allowed to use IOCCC content?](#faq6_11)
 
 
 # The IOCCC FAQ
@@ -2445,6 +2452,12 @@ we request that you ask the [IOCCC judges](judges.html) first.
 Please send your request using the instructions on the [contacting
 the IOCCC Judges](/contact.html) page.
 
+Please note that the content of the IOCCC is [Copyrighted and is under
+the CC BY-SA 4.0 License](#copyright).
+
+See [FAQ 6.11](#license) for additional information on the
+[Copyright and CC BY-SA 4.0 License](license.html).
+
 
 ### <a name="faq6_4"></a>FAQ 6.4: Why do you sometimes use the first person plural?
 
@@ -3373,6 +3386,37 @@ example, you would type:
 This will merge your pull request to your fork.
 
 
+### <a name="faq6_11"></a><a name="license"></a>FAQ 6.11: Am I allowed to use IOCCC content?
+
+**Disclaimer**: This FAQ is **not a license**, has **no legal
+value**, and only highlights some of the key features and terms of
+the actual [CC BY-SA 4.0
+license](https://creativecommons.org/licenses/by-sa/4.0/legalcode.en).
+
+The content of the IOCCC is [Copyrighted and is under the CC BY-SA 4.0 License](#copyright).
+
+As long as you abide by the terms of the [CC BY-SA 4.0
+License](https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1)
+you may copy and redistribute the material in any medium or format
+for any purpose, even commercially.
+
+As long as you abide by the terms of the [CC BY-SA 4.0
+License](https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1)
+you may remix, transform, and build upon the material for any
+purpose, even commercially.
+
+This FAQ is an incomplete summary of how you may use IOCCC content.
+You should review the [highlights of some of the key features and terms](license.html)
+and this may help clarify some aspects of the
+[CC BY-SA 4.0 License](https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1).
+
+The [Copyright and CC BY-SA 4.0 License](#copyright) 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.
+
+
 <!--
 
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