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.

archive/historic/README.md

@@ -79,7 +79,7 @@ Machine](https://web.archive.org) as of [2022 Dec
 
 *HINT*: To uncompress a given bzip2 compressed tarball file, use:
 
-```sh
+```<!---sh-->
 tar -jxvf file.tar.bz2
 ```
 
@@ -88,7 +88,7 @@ where "_file.tar.bz2_" is the name of a file found in this directory.
 To uncompress all of the 2022 Dec 28 archive using the year based
 bzip2 compressed tarball files:
 
-```sh
+```<!---sh-->
 for year in 198{4,5,6,7,8,9} 199{0,1,2,3,4,5,6,8} 200{0,1,4,5,6} 201{1,2,3,4,5,8,9} 2020; do
     rm -rf "$year"
     tar -jxvf "archive-$year.tar.bz2"

archive/historic/index.html

@@ -191,14 +191,14 @@ Machine</a> as of [2022 Dec
 28)(https://web.archive.org/web/20201228005211/https://www.ioccc.org/).</p>
 <h2 id="how-to-unpack">How to unpack</h2>
 <p><em>HINT</em>: To uncompress a given bzip2 compressed tarball file, use:</p>
-<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">tar</span> <span class="at">-jxvf</span> file.tar.bz2</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>tar -jxvf file.tar.bz2</code></pre>
 <p>where “<em>file.tar.bz2</em>” is the name of a file found in this directory.</p>
 <p>To uncompress all of the 2022 Dec 28 archive using the year based
 bzip2 compressed tarball files:</p>
-<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="cf">for</span> year <span class="kw">in</span> 198<span class="dt">{4</span><span class="op">,</span><span class="dt">5</span><span class="op">,</span><span class="dt">6</span><span class="op">,</span><span class="dt">7</span><span class="op">,</span><span class="dt">8</span><span class="op">,</span><span class="dt">9}</span> 199<span class="dt">{0</span><span class="op">,</span><span class="dt">1</span><span class="op">,</span><span class="dt">2</span><span class="op">,</span><span class="dt">3</span><span class="op">,</span><span class="dt">4</span><span class="op">,</span><span class="dt">5</span><span class="op">,</span><span class="dt">6</span><span class="op">,</span><span class="dt">8}</span> 200<span class="dt">{0</span><span class="op">,</span><span class="dt">1</span><span class="op">,</span><span class="dt">4</span><span class="op">,</span><span class="dt">5</span><span class="op">,</span><span class="dt">6}</span> 201<span class="dt">{1</span><span class="op">,</span><span class="dt">2</span><span class="op">,</span><span class="dt">3</span><span class="op">,</span><span class="dt">4</span><span class="op">,</span><span class="dt">5</span><span class="op">,</span><span class="dt">8</span><span class="op">,</span><span class="dt">9}</span> 2020<span class="kw">;</span> <span class="cf">do</span></span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="fu">rm</span> <span class="at">-rf</span> <span class="st">&quot;</span><span class="va">$year</span><span class="st">&quot;</span></span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a>    <span class="fu">tar</span> <span class="at">-jxvf</span> <span class="st">&quot;archive-</span><span class="va">$year</span><span class="st">.tar.bz2&quot;</span></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="cf">done</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>for year in 198{4,5,6,7,8,9} 199{0,1,2,3,4,5,6,8} 200{0,1,4,5,6} 201{1,2,3,4,5,8,9} 2020; do
+    rm -rf &quot;$year&quot;
+    tar -jxvf &quot;archive-$year.tar.bz2&quot;
+done</code></pre>
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