set pandoc 8 character tab stops for HTML conversion

We add `--tab-stop=8` to all `pandoc(1)` executions in order to set
a better tab stop indentation, especially for tab intended code blocks.

Changed `bin/pandoc-wrapper.sh` VERSION "1.5.3 2024-03-26"
to "1.6 2024-03-31".

Fixed `1991/brnstnd/sorta.README.md` so that the sorta code
is code blocks.

Removed unneeded paragraph group in copyright in `inc/footer.default.html`.

Performed `make www` to perform the above and test under macOS.

2012/blakely/index.html

@@ -178,15 +178,15 @@ to a maximum of 250.</p>
 <p>The expressions are written in <a href="https://en.wikipedia.org/wiki/Reverse_Polish_notation">Reverse Polish
 Notation</a> with the
 following characters recognised:</p>
-<pre><code>+, -, *, /      - usual arithmetic operations
-^           - Exponentiation; valid for constant exponent only
-s           - sin
-c           - cos
-0-9         - single digit integers
-d           - duplicate number on stack
-t           - transpose top two elements on stack
-x           - x coordinate value
-y           - y coordinate value</code></pre>
+<pre><code>+, -, *, /          - usual arithmetic operations
+^                   - Exponentiation; valid for constant exponent only
+s                   - sin
+c                   - cos
+0-9                 - single digit integers
+d                   - duplicate number on stack
+t                   - transpose top two elements on stack
+x                   - x coordinate value
+y                   - y coordinate value</code></pre>
 <p>NB: all arithmetic is done in double precision, so <code>23/</code> is two-thirds, rather
 than 0.</p>
 <p>The surface plotted corresponds to <code>-1 &lt;= x,y &lt;= 1</code> and for best results, the
@@ -243,11 +243,11 @@ questions.)</p>
 
     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)
+        Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
 
     For more information, see:
 
-    https://creativecommons.org/licenses/by-sa/4.0/
+        https://creativecommons.org/licenses/by-sa/4.0/
 
 -->
 
@@ -310,7 +310,7 @@ questions.)</p>
 <div class="footer">
   <h2>Copyright and CC BY-SA 4.0 License</h2>
   <p>This file and web page is:</p>
-  <blockquote><p><b>Copyright &copy; 1984-2024 by Landon Curt Noll. All Rights Reserved.</b></p></blockquote>
+  <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>