Merge pull request #312 from adjust/readme_update

Readme update

Author: uerceg

README.md

@@ -193,6 +193,7 @@ The Google Play Store `INSTALL_REFERRER` intent should be captured with a broadc
 ```xml
 <receiver
     android:name="com.adjust.sdk.AdjustReferrerReceiver"
+    android:permission="android.permission.INSTALL_PACKAGES"
     android:exported="true" >
     <intent-filter>
         <action android:name="com.android.vending.INSTALL_REFERRER" />

doc/english/referrer.md

@@ -25,6 +25,7 @@ also need to update your `AndroidManifest.xml` to use your own
 ```xml
 <receiver
     android:name="com.your.app.InstallReceiver"
+    android:permission="android.permission.INSTALL_PACKAGES"
     android:exported="true" >
     <intent-filter>
         <action android:name="com.android.vending.INSTALL_REFERRER" />