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.

1989/jar.1/README.md

@@ -3,7 +3,7 @@
 NOTE: this will run the program itself.
 
 ```sh
-make clobber all
+    make clobber all
 ```
 
 There is an alternate version with a slight difference that you may wish to try.
@@ -13,7 +13,7 @@ See the [Alternate code](#alternate-code) section below for more details.
 ## To use:
 
 ```sh
-./jar.1
+    ./jar.1
 ```
 
 
@@ -27,14 +27,14 @@ This alternate code, which prints something slightly different, is provided as w
 NOTE: this will run the program itself.
 
 ```sh
-make clobber alt
+    make clobber alt
 ```
 
 
 ### Alternate use:
 
 ```sh
-./jar.1.alt
+    ./jar.1.alt
 ```
 
 
@@ -44,7 +44,7 @@ On many systems the compiler will not allow you to send the object file to
 `/dev/tty`.  The author suggested:
 
 ```sh
-cc -c -o /dev/tty jar.1.c
+    cc -c -o /dev/tty jar.1.c
 ```
 
 As a last resort the `jar.1.sh` script provided simulates