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.

1998/schweikh2/README.md

@@ -54,7 +54,7 @@ make schweikh2
 
 often produced an error of the form:
 
-```
+```sh
 gcc -ansi schweikh2.alt.c -o schweikh2.alt
 as: Error: cca00NzV.s, line 58: Missing " at end of string
      "