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.

2001/coupard/README.md

@@ -1,20 +1,20 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./coupard
 ```
 
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -52,7 +52,7 @@ that can do sound, as a lowest-denominator sound I/O interface.
 
 To listen to what the program says directly, invoke
 
-```sh
+```<!---sh-->
     ./coupard > /dev/audio
 ```
 
@@ -68,7 +68,7 @@ If you want to convert the audio output of the program into another audio
 format, you can pipe it to [SoX](https://en.wikipedia.org/wiki/SoX) for example
 (`sox` is the Swiss army knife of Unix audio tools). The command:
 
-```sh
+```<!---sh-->
     ./coupard | sox -c1 -r8000 -tub - -c2 -r44100 -twav test.wav
 ```
 

2001/coupard/index.html

@@ -141,11 +141,11 @@ Location: <a href="../../location.html#ZZ">ZZ</a> - <em>Unknown location</em></l
 <!-- 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>
 <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">./coupard</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./coupard</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>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>You may need to run this a few times to understand exactly what is
 being said. You might even need to look somewhere on your desktop,
@@ -170,7 +170,7 @@ fixed-format audio interface that is supported by the majority of Unices
 that can do sound, as a lowest-denominator sound I/O interface.</p>
 <h3 id="program-usage">Program usage</h3>
 <p>To listen to what the program says directly, invoke</p>
-<div class="sourceCode" id="cb4"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./coupard</span> <span class="op">&gt;</span> /dev/audio</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./coupard &gt; /dev/audio</code></pre>
 <p>The program then speaks out something like</p>
 <blockquote>
 <p>The time is HH hours MM minutes SS seconds</p>
@@ -181,7 +181,7 @@ the speakers connected … :-)</p>
 <p>If you want to convert the audio output of the program into another audio
 format, you can pipe it to <a href="https://en.wikipedia.org/wiki/SoX">SoX</a> for example
 (<code>sox</code> is the Swiss army knife of Unix audio tools). The command:</p>
-<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">./coupard</span> <span class="kw">|</span> <span class="fu">sox</span> <span class="at">-c1</span> <span class="at">-r8000</span> <span class="at">-tub</span> <span class="at">-</span> <span class="at">-c2</span> <span class="at">-r44100</span> <span class="at">-twav</span> test.wav</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./coupard | sox -c1 -r8000 -tub - -c2 -r44100 -twav test.wav</code></pre>
 <p>converts the output of the program into a 44.1KHz stereo .WAV
 file and saves it into <code>test.wav</code>.</p>
 <p>The output format of the program is 8KHz, unsigned 8-bit samples.</p>