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.

1998/dlowe/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make all
 ```
 
@@ -10,7 +10,7 @@ below for more details.
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./dlowe < file > pootfile
 
     ./dlowe < file
@@ -30,7 +30,7 @@ For more detailed information see [1998 dlowe bugs](../../bugs.html#1998_dlowe).
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./dlowe < README.md
     ./dlowe < README.md > README.poot.md
 ```
@@ -39,7 +39,7 @@ Why is there different output?
 
 Also try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -54,7 +54,7 @@ that program.
 
 ### Alternate build:
 
-```sh
+```<!---sh-->
     make alt
 ```
 
@@ -70,7 +70,7 @@ What's the difference between this and `dlowe`?
 
 ### Alternate try:
 
-```sh
+```<!---sh-->
     ./try.alt.sh
 ```
 
@@ -93,7 +93,7 @@ more consistent level of quality.  :-)
 
 A CGI script such as:
 
-```sh
+```<!---sh-->
     #!/bin/sh
     # pootify - a sample CGI pootifier
     #
@@ -131,7 +131,7 @@ should use the above one instead. You can use the script
 [pootify.sh](pootify.sh), however, to download and generate html files that you
 can look at locally in a browser or pipe through `less(1)`. For instance:
 
-```sh
+```<!---sh-->
     ./pootify.sh URL=https://microsoft.com | less
 
     ./pootify.sh -r URL=https://microsoft.com > ms.html
@@ -143,7 +143,7 @@ it in a browser.
 
 For an old example of it working as a CGI script see:
 
-```sh
+```<!---sh-->
     https://web.archive.org/web/20040326083431/http://www.pootpoot.com/poot/pootify/?URL=http%3A%2F%2Fwww.ioccc.org
 ```