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.

2012/zeitak/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -10,7 +10,7 @@ code](#alternate-code) below.
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./zeitak < file
 ```
 
@@ -21,7 +21,7 @@ text files that are not code.
 
 ## Try:
 
-```sh
+```<!---sh-->
     make test
 ```
 
@@ -38,7 +38,7 @@ understand this extremely subtle entry.
 
 ### Alternate build:
 
-```sh
+```<!---sh-->
     make alt
 ```
 
@@ -92,7 +92,7 @@ around it's position.
 * Ignores parenthesis inside strings or character constants, so no errors
   will be detected in the following line:
 
-```c
+```<!---c-->
     printf(")");
 ```
 
@@ -104,7 +104,7 @@ around it's position.
 * Escapes (e.g. `\"`) are ignored, so the following line will produce
   an error:
 
-```c
+```<!---c-->
     printf("\"");
 ```