refactoring: description added

src/convert_cm_in_dm.c

@@ -1,7 +1,7 @@
 
 #include "convert_cm_in_dm.h"
 #include <stdio.h>
-//convert length for double
+//convert length for double cm into dm
 double cm_to_dm(double cm) {
     return cm / 10.0;
 }