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.

1993/plummer/README.md

@@ -5,6 +5,7 @@ Mark Plummer
 Fallston, MD, 21047  
 US  
 
+
 ## To build:
 
 ```sh
@@ -25,6 +26,7 @@ where:
 
 NOTE: an alternate version exists. See Alternate code section below.
 
+
 ## Try:
 
 ```sh
@@ -34,9 +36,7 @@ NOTE: an alternate version exists. See Alternate code section below.
 
 ### Alternate code:
 
-[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) added an alternate
-version which uses `usleep()` so you can see what is happening with faster
-systems. To use:
+To use:
 
 
 ```sh
@@ -51,19 +51,19 @@ If you wish to change the time to sleep (default `200`) you can do so like:
 make clobber CDEFINE="-DZ=50" alt
 ```
 
+
 #### Try:
 
 ```sh
 ./plummer.alt xyzzyzzyx 5555
 ```
 
-Thank you Cody!
-
 ### INABIAF - it's not a bug it's a feature :-)
 
 This entry will very likely crash or do something else if you run it without
 enough args.
 
+
 ## Judges' remarks:
     
 For extra credit: What happens when 'number' contains non-numeric
@@ -122,6 +122,7 @@ The inspiration for this program came from actual code which dealt
 with scanning for a unique temporary filename by appending a
 successively larger number to the end of a string.
 
+
 ## Copyright and CC BY-SA 4.0 License:
 
 This file is Copyright (c) 2023 by Landon Curt Noll.  All Rights Reserved.