improved indentation and whitespace for markdown code blocks

All code blocks in markdown have been intended by at least 4 spaces.

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 from "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`.

Fixed excess whitespace after list Author on entry `index.html` page.

Changed `bin/output-index-author.sh` VERSION from "1.5.2 2024-03-26"
to "1.6 2024-03-31".

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

TODO: Fix the problem of the initial line of code being extra intended.
TODO: Fix excess whitespace around code that is inline.

2015/index.html

@@ -169,18 +169,18 @@ one of the all time best IOCCC entries from 1984.</p>
 would have been much higher had some people paid attention to rules 2
 and 22 (one third of 666).</p>
 <p>Rule 22, now known as <strong>Catch 22</strong> states:</p>
-<pre><code>|  22) Your source code, data files, remarks and program output must NOT
-|      identify the authors of your code.  The judges STRONGLY prefer to
-|      not know who is submitting entries to the IOCCC.
+<pre><code>    |  22) Your source code, data files, remarks and program output must NOT
+    |      identify the authors of your code.  The judges STRONGLY prefer to
+    |      not know who is submitting entries to the IOCCC.
 
-|      The &quot;Peter Honeyman is exempt&quot; guideline also applies to this rule.
-|      Identifying yourself, in an obvious way in your code, data, remarks
-|      or program output, unless you are Peter Honeyman or pretending
-|      to be Peter Honeyman, will be grounds for disqualification of your entry.</code></pre>
+    |      The &quot;Peter Honeyman is exempt&quot; guideline also applies to this rule.
+    |      Identifying yourself, in an obvious way in your code, data, remarks
+    |      or program output, unless you are Peter Honeyman or pretending
+    |      to be Peter Honeyman, will be grounds for disqualification of your entry.</code></pre>
 <p>A number of other entries were based on <a href="iocccsize.c">iocccsize.c</a>, making
 derivative works rather than original works.</p>
 <p>Still other entries were too large, violating the first line of rule 2:</p>
-<pre><code>2) The size of your program source must be &lt;= 4096 bytes in length.</code></pre>
+<pre><code>    2) The size of your program source must be &lt;= 4096 bytes in length.</code></pre>
 <p>While these entries might have passed under the 2053 limit for iocccsize,
 they were larger than &lt;= 4096 bytes, sometimes by an order or magnitude.</p>
 <p>We hope the authors of some of those entries will fix and re-submit