Add @Expensify to React Native incubating partners list (#37497)

Summary:
Adding Expensify to the React Native incubating partners list

## Changelog:

<!-- Help reviewers and the release process by writing your own changelog entry.

Pick one each for the category and type tags:

[ANDROID|GENERAL|IOS|INTERNAL] [BREAKING|ADDED|CHANGED|DEPRECATED|REMOVED|FIXED|SECURITY] - Message

For more details, see:
https://reactnative.dev/contributing/changelogs-in-pull-requests
-->
[Internal] - Adding Expensify to the React Native incubating partners list

Pull Request resolved: https://github.com/facebook/react-native/pull/37497

Test Plan: N/A - Just documentation update

Reviewed By: TheSavior

Differential Revision: D47002327

Pulled By: rickhanlonii

fbshipit-source-id: 39adf1e519e32aaf911baacb78a5549109d4c0c0