Added migration guide

README.md

@@ -282,6 +282,16 @@ Installation
 3. Add Target **PAYFormBuilder** to your *Target Dependencies* list.
 4. `import <PAYFormBuilder/PAYFormBuilder.h>` wherever you want to use the components. You could add it to your Prefix header file, if you want.
 
+Migration
+---------
+### 1.x -> 2.x
+* `PAYFormButton` now has a `label` property instead of `titleLabel`
+* `PAYFormView` (and it's subclasses `PAYFormButton`, `PAYFormSingleLineTextField`, etc.) now has a `cell` property, which allows to configure or replace the cell. Still use the `view` property to add subviews.
+* The names of the `PAYFormButtonStyle`s were [changed](https://github.com/Eldorado234/PAYFormBuilder/commit/b0c297c1ef233cd90965226d6aaf243adc1e7641)
+* All frame calculations were replaced by auto layout, so frames should't be set manually anymore
+* `initWithFrame:` calls should be removed  
+* Use the all new theming API to style your forms
+
 Requirements
 ------------
 * iOS 7+