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.

1985/sicherman/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make all
 ```
 
@@ -11,7 +11,7 @@ more details on it.
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./sicherman < file
 
     echo foo | ./sicherman
@@ -23,7 +23,7 @@ more details on it.
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -43,7 +43,7 @@ audience.
 Although this will be built if the original fails to compile you can do it
 manually like:
 
-```sh
+```<!---sh-->
     make alt
 ```
 
@@ -52,14 +52,14 @@ In this case it will be built as `sicherman.alt`.
 
 ### Alternate use:
 
-```sh
+```<!---sh-->
     ./sicherman.alt < file
 ```
 
 
 ### Alternate try:
 
-```sh
+```<!---sh-->
     ./try.alt.sh
 ```
 
@@ -80,7 +80,7 @@ on a line.  Now enter the letters 'n' through 'z'.  But to borrow a quote
 from Richard Stallman: If you think you understand what this code
 does, then you don't, so read it again!  Explain why:
 
-```sh
+```<!---sh-->
     ./sicherman < sicherman.c | ./sicherman | diff - ./sicherman.c
 ```