Update Readme for 1.2.0

Author: zxcpoiu

README.md

@@ -141,6 +141,65 @@ DeviceEventEmitter.addListener('Proximity', function (data) {
 
 ```
 
+## About Permission:
+
+
+since version 1.2.0, two functions and a property were added:
+
+```javascript
+// --- function
+async checkRecordPermission() // return promise
+async requestRecordPermission() // return promise
+
+// --- property
+recordPermission = 'unknow' or 'granted' or 'denied', default is 'unknow'
+```
+
+After incall-manager initialized, it will check current state of record permission and set to `recordPermission` property.
+so you can just write below code in your `ComponentDidMount` like:
+
+```javascript
+if (InCallManager.recordPermission !== 'granted') {
+    InCallManager.requestRecordPermission()
+    .then((requestedRecordPermissionResult) => {
+        console.log("InCallManager.requestRecordPermission() requestedRecordPermissionResult: ", requestedRecordPermissionResult);
+    })
+    .catch((err) => {
+        console.log("InCallManager.requestRecordPermission() catch: ", err);
+    });
+}
+```
+
+**NOTE for android:**
+
+React Native does not officially support api 23 currently ( it is on api 22 now. see: [RN known issues](https://facebook.github.io/react-native/docs/known-issues.html#android-m-permissions)) and android supports request permission at runtime since api 23, so it will always return 'granted' immediately after calling `checkRecordPermission()` or `requestRecordPermission()`.
+
+If you really need the functionality, you can do the following to make them work but at your own risk:  
+( I've tested it though, but who knows :) )
+
+Step 1: change your `targetSdkVersion` to 23 in `$your_project/android/app/build.gradle`  
+Step 2: override `onRequestPermissionsResult` in your `MainActivity.java` like:  
+
+```
+    @Override
+    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+        InCallManagerPackage.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+    }
+```
+
+then you can test it on android 6 now.
+
+**Another thing you should know is:**
+
+If you change targetSdkVersion to 23, the `red box` which React Native used to display errors in development mode requires permission `Draw Over Other Apps`.  
+So in **development mode**, you should manually grant permission in `app settings` on your device or declare `android.permission.SYSTEM_ALERT_WINDOW` in your manifest.  
+You don't have to do this in **release mode** since there are no red box.  
+
+
+checkout this awesome project: [react-native-android-permissions](https://github.com/lucasferreira/react-native-android-permissions) by @lucasferreira for more information.
+
+
 ## Automatic Basic Behavior:
 
 **on start:**  
@@ -176,6 +235,8 @@ note: ios only supports `auto` currently.
 | setSpeakerphoneOn(`enable: ?boolean`)   | :smile: | :rage: | toggle speaker ON/OFF once. but not force</br>default: false |
 | setForceSpeakerphoneOn(`flag: ?boolean`)   | :smile: | :smile: | true -> force speaker on</br> false -> force speaker off</br> null -> use default behavior according to media type</br>default: null |
 | setMicrophoneMute(`enable: ?boolean`)   | :smile: | :rage: | mute/unmute micophone</br>default: false |
+| async checkRecordPermission()   | :smile: | :smile: | check record permission without promt. return Promise. see **about permission** section above |
+| async requestRecordPermission()   | :smile: | :smile: | request record permission to user. return Promise. see **about permission** section above |
 
 **Events**
 
@@ -192,7 +253,7 @@ be care when customize your own behavior**
 
 ## LICENSE:
 
-**[ICS License](https://opensource.org/licenses/ISC)** ( functionality equivalent to **MIT License** )
+**[ISC License](https://opensource.org/licenses/ISC)** ( functionality equivalent to **MIT License** )
 
 ## Contributing: