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/endoh2/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./endoh2 > pi.c
     gcc -o pi pi.c
     ./pi > 314.c
@@ -15,7 +15,7 @@
 
 and:
 
-```sh
+```<!---sh-->
     ./endoh2 e > e.c\
     gcc -o e e.c
     ./e > 271.c
@@ -26,7 +26,7 @@ and:
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -112,7 +112,7 @@ characters and not requiring a return in `main()`.  In fact, recent compilers
 with `-std=c99 -Wall -W -Wextra -pedantic` would say nothing.
 
 
-```sh
+```<!---sh-->
     gcc -std=c99 -Wall -W -Wextra -pedantic spigot.c
     clang -std=c99 -Wall -W -Wextra -pedantic spigot.c
 ```
@@ -123,7 +123,7 @@ and gcc-4.5.3 and clang-3.1 on Cygwin.
 
 ### Synopsis
 
-```sh
+```<!---sh-->
     cc endoh2.c -o endoh2
 
     ./endoh2 > pi.c