Merge pull request #195 from yonahforst/readme.-NSPhotoLibraryAddUsageDescription

Add `NSPhotoLibraryAddUsageDescription` for Info.plist doc

README.md

 <string>Some description</string>
 <key>NSLocationWhenInUseUsageDescription</key>
 <string>Some description</string>
+<key>NSPhotoLibraryAddUsageDescription</key>
+<string>Some description</string>
 <key>NSPhotoLibraryUsageDescription</key>
 <string>Some description</string>
 <key>NSSpeechRecognitionUsageDescription</key>