improve how markdown code language is commented

We added a space between the markdown triple code mark
and language that was enclosed in HTML comments.

So a line of the form:

````
```<!---c--->
````

became:

````
``` <!---c--->
````

This was done to **help** some code see that the HTML comment
string was not a markdown code specifier.   Not all code
understands this after this changed.  For example, `pandoc(1)`
still forms HTML classes of the form "&lt;!---c--&gt;"
when it encounters the above mentioned change.

We also fixed a problem with `2019/dogon/README.md` regarding
a markdown code block.

We also fixed a problem with `2020/yang/README.md` regarding
a markdown code block.

1991/README.md

@@ -35,7 +35,7 @@ been eliminated, and will likely be considered in future years.
 
 A number of entries made use of the following C pre-processor feature:
 
-```<!---c-->
+``` <!---c-->
     #define X define
     #X foo bar
 ```

1991/ant/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
@@ -10,7 +10,7 @@ familiar to vi(m) users.
 
 ## To use:
 
-```<!---sh-->
+``` <!---sh-->
     ./ant some_file
 ```
 
@@ -20,12 +20,12 @@ program exit without doing anything.
 
 ## Try:
 
-```<!---sh-->
+``` <!---sh-->
     make hill
     ./ant hill
 ```
 
-```<!---sh-->
+``` <!---sh-->
     make mole
     ./ant mole
 ```
@@ -46,7 +46,7 @@ rest was unchanged.
 
 ### Alternate build:
 
-```<!---sh-->
+``` <!---sh-->
     make alt
 ```
 

1991/brnstnd/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
 
 ## Try:
 
-```<!---sh-->
+``` <!---sh-->
     ./try.sh
 
     ./sorta < sorta.itailrec

1991/buzzard/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
@@ -21,7 +21,7 @@ For more detailed information see [1991 buzzard bugs](../../bugs.html#1991_buzza
 
 ## To use:
 
-```<!---sh-->
+``` <!---sh-->
     ./buzzard
 ```
 
@@ -37,14 +37,14 @@ code directly so the keys are not made a `-D` at the compiler.
 
 ### Alternate build:
 
-```<!---sh-->
+``` <!---sh-->
     make alt
 ```
 
 
 ### Alternate use:
 
-```<!---sh-->
+``` <!---sh-->
     ./buzzard.alt
 ```
 
@@ -89,7 +89,7 @@ so make sure to convert tabs to spaces before using it.
 
 Usage:
 
-```<!---sh-->
+``` <!---sh-->
     ./buzzard [filename [escape-char [start-x start-yNNN
 ```
 

1991/cdupont/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
 
 ## To use:
 
-```<!---sh-->
+``` <!---sh-->
     ./cdupont
 ```
 
@@ -16,7 +16,7 @@
 
 Why is the following label necessary?
 
-```<!---c-->
+``` <!---c-->
     sorryfor_this_unused_but_very_needed_label:
 ```
 

1991/davidguy/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
 
 ## To use:
 
-```<!---sh-->
+``` <!---sh-->
     ./davidguy ip_address:server.screen
 ```
 
@@ -16,7 +16,7 @@ where `ip_address` in an IP address of an X server.
 
 ## Try:
 
-```<!---sh-->
+``` <!---sh-->
     ./davidguy 127.0.0.1:0.0
 ```
 
@@ -24,7 +24,7 @@ Of course, you may need to supply a more reasonable address.  :-)
 
 ## Also try:
 
-```<!---sh-->
+``` <!---sh-->
     cp -f davidguy guydavid
     ./guydavid 127.0.0.1:0.0
 ```

1991/dds/README.md

@@ -1,13 +1,13 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
 
 ## To use:
 
-```<!---sh-->
+``` <!---sh-->
     ./dds basic_program
     ./a.out 2>/dev/null
 ```
@@ -17,7 +17,7 @@
 
 The author suggests trying:
 
-```<!---sh-->
+``` <!---sh-->
     ./dds LANDER.BAS
     ./a.out
 ```
@@ -27,7 +27,7 @@ produced?  How does `a.c` relate to [LANDER.BAS](LANDER.BAS)?
 
 What happens if you give the program a C program like itself? Try:
 
-```<!---sh-->
+``` <!---sh-->
     ./dds dds.c
 ```
 

1991/fine/README.md

@@ -1,20 +1,20 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
 
 ## To use:
 
-```<!---sh-->
+``` <!---sh-->
     echo text | ./fine
 ```
 
 
 ## Try:
 
-```<!---sh-->
+``` <!---sh-->
     ./try.sh
 ```
 

1991/rince/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
@@ -11,7 +11,7 @@ that's fewer than the original program.
 
 ## To use:
 
-```<!---sh-->
+``` <!---sh-->
     ./rince
 ```
 
@@ -30,7 +30,7 @@ The author set the maximum number of moves to 484.
 
 ### Alternate build:
 
-```<!---sh-->
+``` <!---sh-->
     make alt
 ```
 
@@ -41,7 +41,7 @@ configurable maximum number of moves allowed, defaulting to the entry's max,
 
 To reconfigure the maximum number of moves to 700:
 
-```<!---sh-->
+``` <!---sh-->
     make clobber MAXMOVES=700 alt
 ```
 
@@ -50,13 +50,13 @@ To reconfigure the maximum number of moves to 700:
 
 To run the first alt version:
 
-```<!---sh-->
+``` <!---sh-->
     ./rince.alt
 ```
 
 To run the second alt version:
 
-```<!---sh-->
+``` <!---sh-->
     ./rince.alt2
 ```
 

1991/westley/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```<!---sh-->
+``` <!---sh-->
     make all
 ```
 
@@ -27,7 +27,7 @@ for the interested. See the [try](#try) section if you just want to play.
 Make and then run as follows:
 
 
-```<!---sh-->
+``` <!---sh-->
     ./westley [move_location] | tee nextmove.c
 ```
 
@@ -43,7 +43,7 @@ a move on a tic-tac-toe board:
 If you omit `move_location`, then the computer moves first.  For your
 next move, recompile `nextmove.c` and play it again:
 
-```<!---sh-->
+``` <!---sh-->
     make nextmove
     ./nextmove move_location | tee nextmove.c
 ```
@@ -54,7 +54,7 @@ next move, recompile `nextmove.c` and play it again:
 We have provided the shell script, [ttt](ttt.sh), to make it easier to play the
 game:
 
-```<!---sh-->
+``` <!---sh-->
     make ttt
     ./ttt [first_move]	# <- omit first arg to have it move first
     ./ttt next_move
@@ -64,14 +64,14 @@ The shell script determines when the game is over, and automatically replaces
 `merlyn.c` (copied from [westley.c](westley.c) with an improved version after a
 loss).  The [ttt](ttt.sh) script has two other modes:
 
-```<!---sh-->
+``` <!---sh-->
     ./ttt quitgame	# cancel any game in progress, revert to merlyn.c
     ./ttt clobber	# remove all game files, revert to original source
 ```
 
 For example here is a potentially losing game:
 
-```<!---sh-->
+``` <!---sh-->
     ./ttt 1
     ./ttt 4
     ./ttt 6
@@ -80,7 +80,7 @@ For example here is a potentially losing game:
 The final might look like:
 
 
-```<!---c-->
+``` <!---c-->
 		    a(X){/*/X=-		a(X){/*/X=-
 	    X	-1;F;X=-	 	-1;F;X=-
 		    -1;F;}/*/		-1;F;}/*/
@@ -123,7 +123,7 @@ can lose if you cheat. That's supposed to happen. Can you win any other time?
 
 ### Alternate build:
 
-```<!---sh-->
+``` <!---sh-->
     make alt
 ```
 
@@ -194,7 +194,7 @@ function as `a()`, `b()`, or `c()`.  After each function is called, the global
 variables `X` and `O` contain bitmasks of where all the `X`s and `O`s are placed.
 The statement:
 
-```<!---c-->
+``` <!---c-->
     X=-   <char>   -1;
 ```