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.

2015/endoh1/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -11,7 +11,7 @@ require it](../../faq.html#tcpserver).
 
 ## To use:
 
-```sh
+```<!---sh-->
     tcpserver -v 127.0.0.1 10333 ./prog ioccc.txt
 ```
 
@@ -44,7 +44,7 @@ his work.
 
 Compile the program as follows:
 
-```sh
+```<!---sh-->
     cc -O3 -std=c99 \
 	   -Wall -Wextra -pedantic -o prog prog.c \
 	   -Delta_u="Du*laplacian(u)-u*v*v+F*(1-u)" \
@@ -59,7 +59,7 @@ Then, run it with the `tcpserver` command in the
 [Daniel J. Bernstein](../../authors.html#Daniel_J_Bernstein)'s
 [1991/brndstd](../../1991/brnstnd/index.html) "Best of Show".
 
-```sh
+```<!---sh-->
     tcpserver -v 127.0.0.1 10333 ./prog ioccc.txt
 ```