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.

2005/mynx/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -21,7 +21,7 @@ For more detailed information see [2005 mynx bugs](../../bugs.html#2005_mynx).
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./mynx http://<domain>
 ```
 
@@ -31,7 +31,7 @@ the issue of https.
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./mynx http://www.textfiles.com
 
     ./mynx manual.html
@@ -58,7 +58,7 @@ must just appreciate the entry for what it once was.
 
 ### Alternate build:
 
-```sh
+```<!---sh-->
     make alt
 ```
 
@@ -68,7 +68,7 @@ must just appreciate the entry for what it once was.
 Use `mynx.alt` as you would `mynx`. You'd have to specify a port at the end of
 the URL like:
 
-```sh
+```<!---sh-->
     ./mynx.alt https://www.ioccc.org:443
 ```
 
@@ -92,13 +92,13 @@ it inspired me to try my hand at writing the client side complement.
 
 A typical build command would be:
 
-```sh
+```<!---sh-->
     cc -o mynx mynx.c
 ```
 
 While some others like to be a little different:
 
-```sh
+```<!---sh-->
     cc -o mynx mynx.c -lnsl -lsocket
 ```
 
@@ -107,13 +107,13 @@ example, which is kinda of useful when you consider how many OSes put
 all the network functions in a variety of places. So a simpler build
 command sequence would be:
 
-```sh
+```<!---sh-->
     cd source ; ./configure ; make
 ```
 
 After which, the rest of the documentation can be read by saying:
 
-```sh
+```<!---sh-->
     ./mynx ../manual.html
 ```