chore: add migration guides

Author: Joaguirrem

README.md

@@ -148,6 +148,35 @@ Line SDK wrapper for React Native 🚀
     </array>
     ```
 
+## Migration guides
+
+### v3 → v4
+
+1. A `setup` function has been added and needs to be called before using the library.
+    ```typescript
+    Line.setup({ channelId: 'YOUR_CHANNEL_ID' })
+    ```
+
+2. The `getBotFriendshipStatus` function is now called `getFriendshipStatus`.
+
+3. The `refreshToken` function is now called `refreshAccessToken`.
+
+### v4 → v5
+
+1. The file name in the `AppDelegate` import has changed.
+    ```objectivec
+    - #import "RNLine-Swift.h"
+
+    + #import "react_native_line-Swift.h"
+    ```
+
+2. The `login` function now expects an empty object as a default value.
+    ```typescript
+    - Line.login()
+
+    + Line.login({})
+    ```
+
 ## Usage
 
 1. Import the `Line` module: