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.

2005/boutines/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -15,20 +15,20 @@ require it?](../../faq.html#imagemagick).
 Look here to find some [SVG Viewer
 Implementations](https://www.w3.org/Graphics/SVG/WG/wiki/Implementations).
 
-```sh
+```<!---sh-->
     ./boutines < input > output.svg
 ```
 
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
 If `ruby` is installed [try.sh](try.sh) will generate an SVG file by:
 
-```sh
+```<!---sh-->
     ruby -e '20.times{puts "#{rand} #{rand}"}' | ./boutines > test.svg
 ```
 
@@ -75,7 +75,7 @@ an [SVG](https://www.w3.org/TR/SVG11/expanded-toc.html) stream.
 
 This will possibly save a compressed SVG file and may be useful:
 
-```sh
+```<!---sh-->
     ./boutines | gzip > result.svg.gz
 ```