add hack-a-round for language specified markdown code blocks

When language is specified in a markdown code block such as:

````
```c
    printf("Hello, world!\n");
```
````

is used, the resulting HTML as produced by `pandoc(1)` combined
with our revised `ioccc.css` is not intent the code block well.

A temporary "_hack-a-round_" is to turn the "markdown code language
specifier" into an HTML comment.  For example:

````
```<!---c-->
    printf("Hello, world!\n");
```
````

This commits turns off existing markdown code language specifiers
for now, while preserving our ability to restore them in the future
when a better  "_hack-a-round_" to the "markdown code language
specifier" problem is found.

The HTML impact if this "_hack-a-round_" is to produce HTML that
looks like this:

```
<pre class="&lt;!---c--&gt;"><code> .. </code></pre>
```

We might be able to create a complex set of classes for each markdown
code language (there won't be very many) in `ioccc.css`, or we might
find a more general CSS (or maybe `pandoc(1)`?) solution.

For now, this hack-a-round will have to do.

2005/persano/index.html

@@ -141,13 +141,13 @@ Location: <a href="../../location.html#BR">BR</a> - <em>Federative Republic of B
 <!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 
 <h2 id="to-build">To build:</h2>
-<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">make</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make</code></pre>
 <p>There is an alternate version of this entry which should work for Windows by
 setting binary mode on <code>stdout</code>. See <a href="#alternate-code">alternate code</a> below.</p>
 <h2 id="to-use">To use:</h2>
-<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./persano</span> p q [num frames]</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./persano p q [num frames]</code></pre>
 <h2 id="try">Try:</h2>
-<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./try.sh</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./try.sh</code></pre>
 <p>Open the <a href="https://en.wikipedia.org/wiki/GIF">GIF</a> files with a viewer capable of
 displaying animated GIFs and watch closely at the bottom of the picture (you may
 need to use <a href="https://www.lcdf.org/gifsicle/">gifsicle</a> - a great tool to
@@ -162,7 +162,7 @@ let it work with Windows.</p>
 <h3 id="alternate-use">Alternate use:</h3>
 <p>Use <code>persano.alt</code> as you would <code>persano</code> above.</p>
 <h3 id="alternate-try">Alternate try:</h3>
-<div class="sourceCode" id="cb5"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./persano.alt</span> 3 16 <span class="op">&gt;</span> knot3-16.gif</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./persano.alt 3 16 &gt; knot3-16.gif</code></pre>
 <p>Follow the same instructions, using different tools if necessary, as the above
 try section.</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
@@ -179,7 +179,7 @@ linker option).</p>
 <p><strong>knot</strong> writes animated GIF images of rendered <a href="https://en.wikipedia.org/wiki/Torus_knot">torus
 knots</a> to standard output.</p>
 <h3 id="synopsis">SYNOPSIS</h3>
-<div class="sourceCode" id="cb6"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./persano</span> p q [num frames]</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./persano p q [num frames]</code></pre>
 <h3 id="description">DESCRIPTION</h3>
 <p>A <code>(p,q)</code>-<a href="https://en.wikipedia.org/wiki/Torus_knot">torus knot</a> is a closed,
 non-intersecting curve on the surface of a
@@ -190,10 +190,10 @@ resulting curve will <em>not</em> be a knot (that is, imagining the resulting cu
 a loop of rubber, there will be a way to bend, twist and stretch it, without
 cutting it <a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"><sup>1</sup></a>, until it ends up looking just like a circle embedded in R3 <a href="#fn2" class="footnote-ref" id="fnref2" role="doc-noteref"><sup>2</sup></a>).</p>
 <p>Sample usage:</p>
-<div class="sourceCode" id="cb7"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./persano</span> 3 2 1 <span class="op">&gt;</span> foo.gif</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./persano 3 2 1 &gt; foo.gif</code></pre>
 <p>writes a non-animated GIF (a single frame) stream of a rendered trefoil
 knot to the file <code>foo.gif</code>.</p>
-<div class="sourceCode" id="cb8"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./persano</span> 5 2</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./persano 5 2</code></pre>
 <p>writes a GIF stream with a rendering of <a href="https://en.wikipedia.org/wiki/Solomon%27s_knot">Solomon’s Seal
 knot</a> to standard
 output; since the number of frames is not specified, an animation with