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.

2004/hibachi/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
 
 ## To use:
 
-```sh
+```<!---sh-->
     cd build; ./hibachi-start.sh &
 ```
 
@@ -42,7 +42,7 @@ There is a `hibachi.tgz` file (NOTE: this file was removed by the judges after
 extraction) that unpacks several support files and a subdirectory tree
 containing the documentation and examples. It can be viewed by:
 
-```sh
+```<!---sh-->
     tar -zxf hibachi.tgz
     lynx hibachi/localhost/index.html
 ```
@@ -58,19 +58,19 @@ To build just the executable:
 
 For Cygwin, FreeBSD, Linux (newer), Mac OS X:
 
-```sh
+```<!---sh-->
     gcc -o hibachi hibachi.c
 ```
 
 For Linux (older):
 
-```sh
+```<!---sh-->
     gcc -DSHUT_WR=1 -o hibachi hibachi.c
 ```
 
 For SunOS:
 
-```sh
+```<!---sh-->
     gcc -o hibachi hibachi.c -lnsl -lsocket
 ```
 
@@ -88,20 +88,20 @@ examples. In which case the preferred build commands are:
 
 To start the server on the default port (8008):
 
-```sh
+```<!---sh-->
     cd build;
     ./hibachi-start.sh &
 ```
 
 To test the server:
 
-```sh
+```<!---sh-->
     lynx http://localhost:8008/
 ```
 
 To stop the server:
 
-```sh
+```<!---sh-->
     kill %1
 ```