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/jason/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./jason
 ```
 
@@ -37,7 +37,7 @@ cause problems. Go ahead, try it! :-)
 TED Shroyer came up with the idea that made it possible to hide all
 the text.  Thanks, TED.  You won.  :)
 
-```sh
+```<!---sh-->
     cc -o jason jason.c
     ./jason
     you are in a maze of twisty little passages

2001/jason/index.html

@@ -141,9 +141,9 @@ Location: <a href="../../location.html#US">US</a> - <em>United States of America
 <!-- 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">./jason</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./jason</code></pre>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>You are in a maze of twisty little passages, all alike.</p>
 <p>The really amazing part of this is that it’s a text adventure, and there’s
@@ -160,13 +160,13 @@ cause problems. Go ahead, try it! :-)</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <p>TED Shroyer came up with the idea that made it possible to hide all
 the text. Thanks, TED. You won. :)</p>
-<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="fu">cc</span> <span class="at">-o</span> jason jason.c</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./jason</span></span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>    <span class="ex">you</span> are in a maze of twisty little passages</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>    <span class="ex">caves</span> lead:  left forward back</span>
-<span id="cb3-5"><a href="#cb3-5" aria-hidden="true" tabindex="-1"></a>    <span class="ex">you</span> see</span>
-<span id="cb3-6"><a href="#cb3-6" aria-hidden="true" tabindex="-1"></a>       <span class="ex">a</span> lamp</span>
-<span id="cb3-7"><a href="#cb3-7" aria-hidden="true" tabindex="-1"></a>    <span class="op">&gt;</span> _</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    cc -o jason jason.c
+    ./jason
+    you are in a maze of twisty little passages
+    caves lead:  left forward back
+    you see
+       a lamp
+    &gt; _</code></pre>
 <p>This program is a rather nostalgic little labyrinth game. Start
 out by typing “<code>get lamp</code>”, then use the direction words “<code>left</code>”,
 “<code>right</code>”, “<code>forward</code>”, and “<code>back</code>” to explore the caves. Note that