docs: update links to forwarded page (#31903)

Summary:
Some of the links in `CONTRIBUTING.md` redirects you to a different page.
I've fixed the links so each link would directly send users to the appropriate page.

## Changelog

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[INTERNAL] [Changed] - update links in CONTRIBUTING.md

Pull Request resolved: https://github.com/facebook/react-native/pull/31903

Test Plan: - [ ] Change links shows the appropriate content

Reviewed By: lunaleaps

Differential Revision: D29933105

Pulled By: GijsWeterings

fbshipit-source-id: b5be74181f8a8e88d8f43e44c469337b7393dedf