move fix thanks a file, update top level html links, rename CONTRIBUTING.md

The fix thank you's have been moved from `README.md` to
`thanks-for-fixes.md`.

**WARNING**: Some mistakes may have been made in doing this.
We presume later changes by others will correct any issues.

The `CONTRIBUTING.md` was renamed `how-to-enter.md`.

A 3rd line of links was added to top level html such as
`contact.html`, `index.html`, `judges.html`, `winners.html`,
and `years.html`.

Improved blank line use in a number (but not all) `README.md` files.

2001/cheong/README.md

@@ -4,19 +4,13 @@ Raymond Cheong
 US  
 <http://www.raymondcheong.com/index.html> 
 
+
 ## To build:
 
 ```sh
 make
 ```
 
-[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed this to work with
-clang by adding another function that is allowed to have a third arg as an int,
-not a `char **`. He chose pain() because it's a four letter word that would
-match the format and because it's pain that clang forces this. :-) This fix
-makes a point of the author's notes on portability no longer valid, btw. Thank
-you Cody for your assistance!
-
 
 ## To run:
 
@@ -37,6 +31,7 @@ This program will very likely crash or do something different without an arg.
 ./cheong 05305265226926441255040573044986873789
 ```
 
+
 ## Judges' remarks:
 
 Be sure to give an even number of digits in the argument.  Add a
@@ -45,6 +40,7 @@ leading 0 if needed.
 The source code is nice, compact, and self documenting
 as all good programs should be!  :-)
 
+
 ## Author's remarks:
 
 ### Operation
@@ -109,6 +105,7 @@ with fixed-width font)
 Thanks goes out to Bobby Rohde for numerous suggestions on how to shorten
 the program.
 
+
 ## Copyright and CC BY-SA 4.0 License:
 
 This file is Copyright (c) 2023 by Landon Curt Noll.  All Rights Reserved.