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.

1993/schnitzi/README.md

@@ -63,7 +63,7 @@ What is cat?
 
 After this program prints the contents of 'file', ask it
 some questions related to the text.
-\
+
 The author suggests the following questions when using
 [schnitzi.info](schnitzi.info):