Small copy change

Hi there, this is a possible alternative to: Improves [ ... ] improvements.
Feel free to ignore :)

All the best,

Michael

README.md

@@ -37,7 +37,7 @@ See https://necolas.github.io/normalize.css/latest/normalize.css
 * Preserves useful defaults, unlike many CSS resets.
 * Normalizes styles for a wide range of elements.
 * Corrects bugs and common browser inconsistencies.
-* Improves usability with subtle improvements.
+* Improves usability with subtle modifications.
 * Explains what code does using detailed comments.