improved indentation and whitespace for markdown code blocks

All code blocks in markdown have been intended by at least 4 spaces.

We add `--tab-stop=8` to all `pandoc(1)` executions in order to set
a better tab stop indentation, especially for tab intended code blocks.

Changed `bin/pandoc-wrapper.sh` VERSION from "1.5.3 2024-03-26"
to "1.6 2024-03-31".

Fixed `1991/brnstnd/sorta.README.md` so that the sorta code
is code blocks.

Removed unneeded paragraph group in copyright in `inc/footer.default.html`.

Fixed excess whitespace after list Author on entry `index.html` page.

Changed `bin/output-index-author.sh` VERSION from "1.5.2 2024-03-26"
to "1.6 2024-03-31".

Performed `make www` to perform the above and test under macOS.

TODO: Fix the problem of the initial line of code being extra intended.
TODO: Fix excess whitespace around code that is inline.

1993/leo/README.md

@@ -1,7 +1,7 @@
 ## To build:
 
 ```sh
-make all
+    make all
 ```
 
 
@@ -10,13 +10,13 @@ make all
 To have the computer guess:
 
 ```sh
-./leo [colors]
+    ./leo [colors]
 ```
 
 To guess the computer's number:
 
 ```sh
-./mind [colors]
+    ./mind [colors]
 ```
 
 where:
@@ -72,35 +72,35 @@ Please don't type ^D at the prompt!!
 ##### EXAMPLE: Suppose we think of 1234
 
 ```
-$ ./leo
-(1296): 6433
-?? 12       # one 3 is a bull, another is a cow, and 4 is a cow
-(160): 5363
-?? 02       # both 3's are cows
-(21): 4231
-?? 22       # 2 and 3 are bulls, 4 and 1 are cows
-(2): 4132
-?? 13       # 3 is a bull; 1, 2 and 4 are cows
-(1): 1234
-?? 40       # you may enter everything there
+    $ ./leo
+    (1296): 6433
+    ?? 12       # one 3 is a bull, another is a cow, and 4 is a cow
+    (160): 5363
+    ?? 02       # both 3's are cows
+    (21): 4231
+    ?? 22       # 2 and 3 are bulls, 4 and 1 are cows
+    (2): 4132
+    ?? 13       # 3 is a bull; 1, 2 and 4 are cows
+    (1): 1234
+    ?? 40       # you may enter everything there
 ```
 
 ##### EXAMPLE: Guess the computer's number
 
 ```
-$ ./mind
-(1296): ???? 1122   # my strategy isn't the best, just as example
-00
-(256): ???? 3344
-20
-(18): ???? 5566
-02
-(6): ???? 3654
-11
-(2): ???? 3355
-00
-(1): ???? 6444
-40		   # we have guessed the number
+    $ ./mind
+    (1296): ???? 1122   # my strategy isn't the best, just as example
+    00
+    (256): ???? 3344
+    20
+    (18): ???? 5566
+    02
+    (6): ???? 3654
+    11
+    (2): ???? 3355
+    00
+    (1): ???? 6444
+    40		   # we have guessed the number
 ```