Clarify FCM SDK swizzling notice (#291)
Clarify FCM SDK swizzling notice (#291)

The previous message was worded in a way as to imply that the FIRAppDelegateProxyEnabled key **should** be set to NO, disabling swizzling. This clarifies that message, indicating that this is for developers who would prefer to manually integrate the SDK.
firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk