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/vanb/README.md

@@ -37,7 +37,6 @@ What happens if you use something other than valid digits?
 
 ## Judges' remarks:
 
-\
 The octal expression may contain:
 
 ```
@@ -93,7 +92,7 @@ what grammar non-terminal to parse. `**O7` is the next character.
 `O3` is an intermediate result. Whenever you see a construct like:
 
 ```
-      !(expression with O2)?
+!(expression with O2)?
 ```
 
 it's decrementing & testing `O2` to see what state it's in. Comparisons