docs(messaging): added note about notifee v7 notification event handling

[RRigueira24]

Description

Adding to docs a note about notifee v7 release impacting react native firebase getInitialNotification and onNotificationsOpenedApp. See https://notifee.app/react-native/docs/release-notes#700

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• I read the Contributor Guide and followed the process outlined there for submitting PRs.
  • Yes
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• I have updated TypeScript types that are affected by my change.
• This is a breaking change;
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Name	Status	Preview	Comments	Updated (UTC)
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[github-actions]

Hello 👋, this PR has been opened for more than 2 months with no activity on it.

If you think this is a mistake please comment and ping a maintainer to get this merged ASAP! Thanks for contributing!

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[mikehardy]

Sorry for the long delay here - these are valid (and Notifee still needs a lot of attention! Getting there, bit by bit...)

[mikehardy]

closing and reopening just to trigger CI

[mikehardy]

added notifee to the spellcheck dictionary - should go green in CI now then can merge

[mikehardy]

what can I say, passing all the various lint checks is harder than it seems!
I think I fixed the last issue - method names will be spell-checked unless in backticks