update RN docs link to reactnative.dev (#28175)

Summary:
Updated React Native docs links to reactnative.dev

## Changelog

[INTERNAL] [CHANGED] - update RN docs links to reactnative.dev
Pull Request resolved: https://github.com/facebook/react-native/pull/28175

Test Plan: Tested new links and made sure they work

Reviewed By: motiz88

Differential Revision: D20114439

Pulled By: cpojer

fbshipit-source-id: 6a7ee32f98da04b440ae31eeb7ea4ee15a23cf22