Update 1990 winning entries' README.md files

Format and typo fixes.

1990/cmills/README.md

@@ -12,7 +12,7 @@ USA
 make all
 ```
 
-## To run
+## To run:
 
 ```sh
 ./cmills [starting_cash]
@@ -23,8 +23,9 @@ work in modern systems (it resulted in a bus error otherwise). Thank you Yusuke
 for your assistance!
 
 [Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) made this safer by
-using `fgets()` instead of `gets()`. This avoids a potentially alarming warning
-at compiling and/or linking and/or runtime. Thank you Cody for your assistance!
+using `fgets()` instead of `gets()`. This avoids an annoying and potentially
+alarming warning at compiling and/or linking and/or runtime that in some cases
+is interspersed with the program's output. Thank you Cody for your assistance!
 
 For the original code see the [1992 archive](/archive/archive-1990.tar.bz2).