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.

2018/giles/README.md

@@ -5,27 +5,27 @@ IOCCC entry that requires SDL1 or SDL2?](../../faq.html#SDL) if you don't have i
 installed and don't know how to do so.
 
 ```sh
-make
+    make
 ```
 
 
 ## To use:
 
 ```sh
-./prog
+    ./prog
 ```
 
 
 ## Try:
 
 ```sh
-./prog ioccc.txt
+    ./prog ioccc.txt
 
-./prog prog.c
+    ./prog prog.c
 
-./prog sand.txt
+    ./prog sand.txt
 
-./prog sand.alt.txt
+    ./prog sand.alt.txt
 ```
 
 NOTE: these invocations will take quite some time to finish.