add 0.70.2 changelog (#34859)

Summary:
Adds changelog for new patch.

## Changelog

<!-- Help reviewers and the release process by writing your own changelog entry. For an example, see:
https://reactnative.dev/contributing/changelogs-in-pull-requests
-->

[Internal] [Changed] - add changelog entry for 0.70.2

Pull Request resolved: https://github.com/facebook/react-native/pull/34859

Test Plan: N/A

Reviewed By: NickGerleman

Differential Revision: D40056094

Pulled By: NickGerleman

fbshipit-source-id: 1e833b63080351c66dafc4e43f3681220a9738eb