Minor typo fixes in 2013/morgan1/README.md

In the year 2013 the IOCCC did not yet have the source code of winning
entries as prog.c but in the remarks it included prog.c (when showing
warnings) so references to prog.c were changed to morgan1.c.

2013/morgan1/README.md

@@ -86,20 +86,20 @@ It also displays the position of 2 famous comets during their last approach:
 With gcc 4.7.2 on Linux Ubuntu 12.10:
 
 ```
-prog.c:38:3: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
-prog.c:40:34: warning: value computed is not used [-Wunused-value]
-prog.c:56:6: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
-prog.c:58:50: warning: value computed is not used [-Wunused-value]
-prog.c:61:5: warning: suggest parentheses around ‘-’ inside ‘>>’ [-Wparentheses]
+morgan1.c:38:3: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
+morgan1.c:40:34: warning: value computed is not used [-Wunused-value]
+morgan1.c:56:6: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
+morgan1.c:58:50: warning: value computed is not used [-Wunused-value]
+morgan1.c:61:5: warning: suggest parentheses around ‘-’ inside ‘>>’ [-Wparentheses]
 ```
 
 With clang 3.1 on Linux Ubuntu 12.10 :
 
 ```
-prog.c:38:49: warning: '&&' within '||' [-Wlogical-op-parentheses]
-prog.c:38:27: warning: '&&' within '||' [-Wlogical-op-parentheses]
-prog.c:55:13: warning: '&&' within '||' [-Wlogical-op-parentheses]
-prog.c:56:14: warning: '&&' within '||' [-Wlogical-op-parentheses]
+morgan1.c:38:49: warning: '&&' within '||' [-Wlogical-op-parentheses]
+morgan1.c:38:27: warning: '&&' within '||' [-Wlogical-op-parentheses]
+morgan1.c:55:13: warning: '&&' within '||' [-Wlogical-op-parentheses]
+morgan1.c:56:14: warning: '&&' within '||' [-Wlogical-op-parentheses]
 ```
 
 This is due to most of the parentheses and braces being removed when