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/kang/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -10,14 +10,14 @@ See [Alternate code](#alternate-code) below for the (fun) rationale here.
 
 ## To use:
 
-```sh
+```<!---sh-->
     echo "full spelling of an English cardinal numeral less than a quadrillion" | ./kang
 ```
 
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh # try various languages
 
     ./en.sh # English 0 through 13
@@ -43,14 +43,14 @@ subtlety of this entry even more.
 
 ### Alternate build:
 
-```sh
+```<!---sh-->
     make alt
 ```
 
 
 ### Alternate use:
 
-```sh
+```<!---sh-->
     echo "full spelling of an English cardinal numeral less than a quadrillion" | ./kang.alt
 
     echo vier | ./kang.alt
@@ -61,7 +61,7 @@ subtlety of this entry even more.
 
 ### Alternate try:
 
-```sh
+```<!---sh-->
     ./try.alt.sh # try various languages
 
     ./en.alt.sh # English 0 through 13
@@ -88,13 +88,13 @@ We've added a linefeed to the print format for convenience.
 
 Can you explain why:
 
-```sh
+```<!---sh-->
     echo f hundr|./kang
 ```
 
 correctly reports 500 but:
 
-```sh
+```<!---sh-->
     echo hundr|./kang
 ```