'Understanding Flutter's keyboard focus system' needs tech and copy review

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Page: https://docs.flutter.dev/ui/interactivity/focus/ Source: https://github.com/flutter/website/tree/main/src/ui/interactivity/focus.m

This conceptual page needs a review or edit by someone relevant with the relevant Flutter framework functionality to make sure it's still up to date and follows best practices. Then after or as part of that, it likely needs a copy edit. While it is an advanced conceptual doc, it likely could benefit from some simplification and more focused sentences.