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.

1990/baruch/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make all
 ```
 
@@ -21,7 +21,7 @@ For more detailed information see [1990 baruch bugs](../../bugs.html#1990_baruch
 
 ## To use:
 
-```sh
+```<!---sh-->
     echo 4 | ./baruch
     echo 7 | ./baruch
 ```
@@ -29,7 +29,7 @@ For more detailed information see [1990 baruch bugs](../../bugs.html#1990_baruch
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -47,7 +47,7 @@ question. YMMV.
 
 ### Alternate build:
 
-```sh
+```<!---sh-->
     make alt
 ```
 

1990/baruch/index.html

@@ -144,7 +144,7 @@ Location: <a href="../../location.html#IL">IL</a> - <em>State of Israel</em> (<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> all</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make all</code></pre>
 <p>There is an alternate version for those using Turbo-C or MSC. See <a href="#alternate-code">alternate
 code</a> below for details.</p>
 <h3 id="bugs-and-misfeatures">Bugs and (Mis)features:</h3>
@@ -152,10 +152,10 @@ code</a> below for details.</p>
 <pre><code>    STATUS: INABIAF - please **DO NOT** fix</code></pre>
 <p>For more detailed information see <a href="../../bugs.html#1990_baruch">1990 baruch bugs</a>.</p>
 <h2 id="to-use">To use:</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="bu">echo</span> 4 <span class="kw">|</span> <span class="ex">./baruch</span></span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">echo</span> 7 <span class="kw">|</span> <span class="ex">./baruch</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    echo 4 | ./baruch
+    echo 7 | ./baruch</code></pre>
 <h2 id="try">Try:</h2>
-<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">./try.sh</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./try.sh</code></pre>
 <h2 id="alternate-code">Alternate code:</h2>
 <p>This alternate code is for the <a href="https://en.wikipedia.org/wiki/0">very few</a>
 <a href="https://en.wikipedia.org/wiki/Microsoft_Windows">users</a>
@@ -165,7 +165,7 @@ the <code>" #Q"</code> string was not changed as that showed worse looking outpu
 of improved output though admittedly we have no way to test the compilers in
 question. YMMV.</p>
 <h3 id="alternate-build">Alternate build:</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="fu">make</span> alt</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make alt</code></pre>
 <h3 id="alternate-use">Alternate use:</h3>
 <p>Use <code>baruch.alt</code> as you would <code>baruch</code>.</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>