add NSPhotoLibraryAddUsageDescription to list of permissions along with an example of how the plist would be updated

Author: geirman

README.md

@@ -36,7 +36,23 @@ IMPORTANT NOTE: You'll still need to perform step 4 for iOS and steps 2 and 5 fo
 1. In the XCode's "Project navigator", right click on your project's Libraries folder ➜ `Add Files to <...>`
 2. Go to `node_modules` ➜ `react-native-image-picker` ➜ `ios` ➜ select `RNImagePicker.xcodeproj`
 3. Add `RNImagePicker.a` to `Build Phases -> Link Binary With Libraries`
-4. For iOS 10+, Add the `NSPhotoLibraryUsageDescription`, `NSCameraUsageDescription`, and `NSMicrophoneUsageDescription` (if allowing video) keys to your `Info.plist` with strings describing why your app needs these permissions. **Note: You will get a SIGABRT crash if you don't complete this step**
+4. For iOS 10+, Add the `NSPhotoLibraryUsageDescription`, `NSCameraUsageDescription`, `NSPhotoLibraryAddUsageDescription` and `NSMicrophoneUsageDescription` (if allowing video) keys to your `Info.plist` with strings describing why your app needs these permissions. **Note: You will get a SIGABRT crash if you don't complete this step**
+
+```
+<plist version="1.0">
+  <dict>
+    ...
+    <key>NSPhotoLibraryUsageDescription</key>
+    <string>$(PRODUCT_NAME) would like access to your photo gallery</string>
+    <key>NSCameraUsageDescription</key>
+    <string>$(PRODUCT_NAME) would like to use your camera</string>
+    <key>NSPhotoLibraryAddUsageDescription</key>
+    <string>$(PRODUCT_NAME) would like to save photos to your photo gallery</string>
+    <key>NSMicrophoneUsageDescription</key>
+    <string>$(PRODUCT_NAME) would like to your microphone (for videos)</string>
+  </dict>
+</plist>
+```
 5. Compile and have fun
 
 #### Android