fix may vs. might README/Makefile issues in years 1984 thru 1998

1990/dds/Makefile

@@ -194,7 +194,7 @@ all: data ${TARGET}
 	supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
-	@echo "NOTE: This entry may not compile when using modern compilers."
+	@echo "NOTE: This entry might not compile when using modern compilers."
 	${CC} ${CFLAGS} $< -o $@ ${LIBS}
 
 # alternative executable