Update README.md

README.md

@@ -45,7 +45,7 @@ wjMagicCurveView.destory();
 // Customize your own curve here
 I create a enum called WJMagicCurveViewParameters, 
 You can create your own WJMagicCurveViewParameters with eight parameters,
-for empty fields, use -1.
+for empty fields, use -1 as default value.
 ```
 
 # Related resource