Merge pull request #423 from cooperka/patch-1

Recommend staying on iOS SDK v3

README.md

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-## NOTE:
-- for latest RN, use latest
-- for RN < 0.40.0, use v2.5.6
-- for RN < 0.33.0, you need to use react-native-fcm@1.1.0
-- for RN < 0.30.0, you need to use react-native-fcm@1.0.15
+## NOTES:
+
+- The new FCM SDK v4.0.0 for iOS is [not yet supported](https://github.com/evollu/react-native-fcm/issues/422); please remain on v3 for now
+- for latest RN, use latest react-native-fcm
+- for RN < 0.40.0, use react-native-fcm@2.5.6
+- for RN < 0.33.0, use react-native-fcm@1.1.0
+- for RN < 0.30.0, use react-native-fcm@1.0.15
 - local notification is not only available in V1
 
 - An example working project is available at: https://github.com/evollu/react-native-fcm/tree/master/Examples/simple-fcm-client