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.

1986/marshall/compilers.md

@@ -55,7 +55,7 @@ The call was:
 
 
 ```c
-_exit(argv[(int)*argc-2/cc[1*(int)*argc]|-1<<4]);
+    _exit(argv[(int)*argc-2/cc[1*(int)*argc]|-1<<4]);
 ```
 
 Changing it to not refer to these variables and just exit 1 and the problems
@@ -73,9 +73,9 @@ After we fix the infinite loop if we change the `_exit()` call in macOS and
 disable the optimiser we might get something like:
 
 ```sh
-$ ./marshall
-      choo choo
-Segmentation fault: 11
+    $ ./marshall
+	  choo choo
+    Segmentation fault: 11
 ```
 
 Observe how it doesn't print it twice. But of course it segfaults so it's not