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.

1984/mullender/README.md

@@ -1,7 +1,7 @@
 # Grand Prize
 
 Sjoerd Mullender\
-<https://github.com/sjoerdmullender>\
+<https://github.com/sjoerdmullender>
 
 Robbert van Renesse