Remove 'America' (A) from 'USA' :-)

This to make the country code consistent with mkiocccentry (and I guess
international standard country codes).

This affects many README.md files and (for one line) winners.csv.

1993/cmills/README.md

@@ -4,7 +4,7 @@ Chris Mills
 Pagine Corporation  
 1961-A Concourse Drive  
 San Jose, CA 95131  
-USA  
+US  
 
 ## To build:
 

1993/ejb/README.md

@@ -4,7 +4,7 @@ E. Jay Berkenbilt
 Engineering Research Associates  
 1595 Springhill Road  
 Vienna, VA 22182-2235  
-USA  
+US  
 
 ## To build:
 

1993/plummer/README.md

@@ -3,7 +3,7 @@
 Mark Plummer  
 2901 Reckord Road  
 Fallston, MD, 21047  
-USA  
+US  
 
 ## To build:
 

1993/schnitzi/README.md

@@ -3,7 +3,7 @@
 Mark Schnitzius  
 1700 Woodbury Rd. #1208  
 Orlando, FL 32828  
-USA  
+US  
 <http://computronium.org/ioccc.html>  
 
 

1993/vanb/README.md

@@ -4,7 +4,7 @@ David Van Brackle
 ISX Corporation  
 1165 Northchase Parkway, Suite 120  
 Marietta, GA 30067  
-USA  
+US  
 
 ## To build: