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.

2013/index.html

@@ -160,9 +160,9 @@ certain comments such as:</p>
 <div class="sourceCode" id="cb2"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>        <span class="op">*</span>\</span>
 <span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>        <span class="op">/</span></span></code></pre></div>
 <p>were not correctly parsed by the tool. The guidelines stated:</p>
-<pre><code>In cases where the above summary and the algorithm implemented by
-the IOCCC size tool source code conflict, the algorithm implemented
-by the IOCCC size tool source code is preferred by the judges.</code></pre>
+<pre><code>    In cases where the above summary and the algorithm implemented by
+    the IOCCC size tool source code conflict, the algorithm implemented
+    by the IOCCC size tool source code is preferred by the judges.</code></pre>
 <p>so this abuse was allowed (and encouraged). The judges hope that
 the IOCCC size tool author will patch the tool to block this kind
 of size abuse in future contests.</p>