update readme

README.md

@@ -80,6 +80,8 @@ macx{
 
 - **```setResizeableAreaWidth(int width = 5)```** can set width of an invisible border aera, inside this aera, window can be resized by mouse.
 
+- **```setResizeable(bool resizeable)```** can set whether the window can be resized by mouse or not.
+
 - Exampleforwindows shows the general usage.
 
 - **WARNING**: resize()/geometry()/setGeometry()/frameGeometry()/frameSize()/x()/y()/.etc function will not works right when the Window is Maximized, try not to use any of these function when the Window is Maximized (If you really want to fix these bugs, feel free to contact [Bringer-of-Light](https://github.com/Bringer-of-Light)) . But these function setContentsMargins()/contentsMargins()/getContentsMargins/contentsRect() can always works right, so you can use them anytime. Generally , it's always a good idea to use Qt Layout Management System instead of hard-code layout Management to avoid potential size-like/pos-like issue.