Update Readme that CAMERA permission is requierd

Developers are lazy, it would help to clarify to new people that normal camera permissions actually are required. Specially under the headline permissions.

README.md

@@ -16,6 +16,10 @@ The comprehensive camera module for React Native. Including photographs, videos,
 - if on react-native >= 0.40 `npm i [email protected]`
 
 ##### Permissions
+To use the camera on Android you must ask for camera permission:
+```java
+  <uses-permission android:name="android.permission.CAMERA" />
+```
 To enable `video recording` feature you have to add the following code to the `AndroidManifest.xml`:
 ```java
   <uses-permission android:name="android.permission.RECORD_AUDIO"/>