Fix Mark Schnitzius's URL in README.md files

As noted in commit 3958bbdb04:

    Updated URL for author as it has changed. It's very little on his
    page and the only page that suggests it is his is the ioccc.html
    page. I couldn't find anything else.

1993/schnitzi/README.md

@@ -4,6 +4,8 @@ Mark Schnitzius
 1700 Woodbury Rd. #1208  
 Orlando, FL 32828  
 USA  
+<http://computronium.org/ioccc.html>  
+
 
 ## To build:
 

1994/schnitzi/README.md

@@ -5,6 +5,8 @@ ISX Corporation
 1165 Northchase Pkwy, Suite 120  
 Marietta, GA 30067  
 USA  
+<http://computronium.org/ioccc.html>
+
 
 ## To build:
 

1995/schnitzi/README.md

@@ -5,6 +5,8 @@
 3215-C Post Woods Dr.  
 Atlanta, GA 30339   
 USA  
+<http://computronium.org/ioccc.html>
+
 
 ## To build:
 

2004/schnitzi/README.md

@@ -5,6 +5,7 @@
 94 Richardson St  
 Albert Park, VIC 3206  
 Australia  
+<http://computronium.org/ioccc.html>  
 
 ## To build: