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.

1998/banks/README.md

@@ -4,7 +4,7 @@ Carl Banks
 Penn State Department of Aerospace Engineering  
 232 Hammond Building  
 University Park, PA 16802  
-USA  
+US  
 <https://blog.aerojockey.com/post/iocccsim>
 
 ## To build:

1998/chaos/README.md

@@ -3,7 +3,7 @@
 Alan De Smet  
 8531 Greenway Blvd. #206  
 Middleton, WI 53562  
-USA  
+US  
 <http://www.highprogrammer.com/alan/>  
 
 

1998/dloweneil/README.md

@@ -4,13 +4,13 @@ David Lowe
 Pootpoot				
 67-D Manchester Street	 
 San Francisco, CA 94110	  
-USA					
+US					
 
 Neil Mix  
 Pootpoot  
 1490 Sacramento Street #4G  
 San Francisco, CA 94110  
-USA  
+US  
 
 ## To build:
 

1998/schnitzi/README.md

@@ -4,7 +4,7 @@ Mark Schnitzius
 ISX Corporation
 1280 West Peachtree St. Apt. 1507
 Atlanta, GA 30309
-USA
+US
 <http://computronium.org/ioccc.html>
 
 ## To build: