cleanup winner README.md files

Fixed cases where there was a bad trailing backslash.

Improved a few cases where a code block was needed
to highlight some text.

Changed a few cases where a code block needed to
declared as, say, a sh code block.

Fixed a few cases where the winner information was not properly formatted.

Plus a few nits and clarifying text was added.

1988/spinellis/README.md

@@ -21,7 +21,7 @@ rm -f spinellis ; cc spinellis.c -o spinellis < input.txt && ./spinellis
 
 and try:
 
-```
+```sh
 rm -f spinellis ; cc spinellis.c -o spinellis < input2.txt && ./spinellis
 ```
 
@@ -36,7 +36,7 @@ cc spinellis.alt.c -o spinellis.alt < input.txt && ./spinellis.alt
 
 and try:
 
-```
+```sh
 cc spinellis.alt.c -o spinellis.alt < input2.txt && ./spinellis.alt
 ```