Update README.md

Author: hackware1993

README.md

@@ -5,7 +5,7 @@ Android and AutoLayout for iOS.
 
 No matter how complex the layout is and how deep the constraints are, it has almost the same
 performance as Flex and Stack. When facing complex layouts, it provides better performance,
-flexibility, and a very flat code hierarchy than Flex and Stack. Say no to 'nesting hell'.
+flexibility, and a very flat code hierarchy than Flex and Stack. Say no to 'nested hell'.
 
 View [Flutter Web Online Example](https://constraintlayout.flutterfirst.cn)