Correct the docs regarding iOS auth methods

[carbonrobot]

As of version 1.5 of AppAuth-iOS, we now use ASWebAuthenticationSession which was released in 7.0.0

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Name	Status	Preview	Comments	Updated (UTC)
react-native-app-auth	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 14, 2024 3:29pm

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