Update README.md

update readme

Author: hackware1993

README.md

@@ -41,7 +41,7 @@ Anyone who sends you a harassing message, you can send him Flutter code and use
     11. baselineToBaseline
 2. margin and goneMargin
 3. clickPadding (quickly expand the click area of child elements without changing their actual size.
-   This means that the click area can be shared between child elements without increasing nesting.)
+   This means that the click area can be shared between child elements without increasing nesting. Sometimes it may be necessary to combine with z-index)
 4. visibility control
 5. constraint integrity hint
 6. bias