[docs] Add RN 0.71 iOS setup on AppDelegate.mm to README.md

[madmeatballs]

[docs] Add RN 0.71 iOS setup on AppDelegate.mm to README.md

• Updated README.md for additional instruction on how to setup your lottie splash screen on AppDelegate.mm now that 0.71 doesn't give access to rootview by default.

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[HwangTaehyun]

@madmeatballs Thank you!! LGTM! Could you change your commit to the following format?

[docs] Add RN 0.71 iOS setup on AppDelegate.mm to README.md

- Updated README.md for additional instruction on how to setup your lottie splash screen on AppDelegate.mm now that 0.71 doesn't give access to rootview by default.

Thank you for your contribution!

[madmeatballs]

Updated the commit message.

[HwangTaehyun]

Oh, What I meant was the real commit message. Sorry. Could you push again after editing?

[madmeatballs]

Oh, What I meant was the real commit message. Sorry. Could you push again after editing?

will do, I'll close this and open an new one