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.

2000/bellard/README.md

@@ -1,14 +1,14 @@
 ## To build:
 
 ```sh
-make
+    make
 ```
 
 
 ## To use:
 
 ```sh
-./bellard
+    ./bellard
 ```
 
 
@@ -23,6 +23,7 @@ Can you modify this code to produce primes such as `23523*2^70000-1`,
 NOTE: as bigger primes are found as time goes by this program no longer prints
 the biggest prime once noted by the author below.
 
+
 ## Author's comments:
 
 This program prints the biggest known prime number (`2^6972593-1`)