Add commentary on recommended token storage libraries

Author: Kadi Kraman

docs/token-storage.md

@@ -20,7 +20,7 @@ In order to use iOS's Keychain services or Android's Secure Shared Preferences,
 
 ## Related OSS libraries
 
-- [react-native-keychain](https://github.com/oblador/react-native-keychain)
-- [react-native-sensitive-info](https://github.com/mCodex/react-native-sensitive-info)
-- [redux-persist-sensitive-storage](https://github.com/CodingZeal/redux-persist-sensitive-storage)
+- [react-native-keychain](https://github.com/oblador/react-native-keychain) - we've had good experiences using this on projects
+- [react-native-sensitive-info](https://github.com/mCodex/react-native-sensitive-info) - secure for iOS, but uses Android Shared Preferences for Android (which is not secure). There is however a fork that uses [Android Keystore](https://github.com/mCodex/react-native-sensitive-info/tree/keystore) which is secure
+- [redux-persist-sensitive-storage](https://github.com/CodingZeal/redux-persist-sensitive-storage) - wraps `react-native-sensitive-info`, see comments above
 - [rn-secure-storage](https://github.com/talut/rn-secure-storage)