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.

2006/toledo1/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./toledo1 [0-9][0-9]
 ```
 
@@ -16,7 +16,7 @@ where `[0-9][0-9]` is a two digit number.
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -38,7 +38,7 @@ visit the 64 squares without repeating them?
 If not, this program does it, just run it with an argument
 giving initial position.
 
-```sh
+```<!---sh-->
     ./toledo1 11       # start is A8
     ./toledo1 18       # start is H8
     ./toledo1 81       # start is A1

2006/toledo1/index.html

@@ -141,12 +141,12 @@ Location: <a href="../../location.html#MX">MX</a> - <em>United Mexican States</e
 <!-- 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">./toledo1</span> <span class="pp">[</span><span class="ss">0</span><span class="pp">-</span><span class="ss">9</span><span class="pp">][</span><span class="ss">0</span><span class="pp">-</span><span class="ss">9</span><span class="pp">]</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./toledo1 [0-9][0-9]</code></pre>
 <p>where <code>[0-9][0-9]</code> is a two digit number.</p>
 <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>For most of the arguments (e.g. those above) the resulting path
 is not circular, but at least one starting point yields a circular path.</p>
@@ -157,11 +157,11 @@ be expected, and some dump core?</p>
 visit the 64 squares without repeating them?</p>
 <p>If not, this program does it, just run it with an argument
 giving initial position.</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">./toledo1</span> 11       <span class="co"># start is A8</span></span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./toledo1</span> 18       <span class="co"># start is H8</span></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./toledo1</span> 81       <span class="co"># start is A1</span></span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./toledo1</span> 88       <span class="co"># start is H1</span></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./toledo1</span> 44       <span class="co"># start is D5</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./toledo1 11       # start is A8
+    ./toledo1 18       # start is H8
+    ./toledo1 81       # start is A1
+    ./toledo1 88       # start is H1
+    ./toledo1 44       # start is D5</code></pre>
 <p>It will print move order. The algorithm is so simple that you can read
 it in the source code. At the first glance it can appear checkered.
 Nevertheless, don’t be dismayed, jar, jar. :-)</p>