Add changelog for 0.76.0-rc.0 (#46419)

Summary:
This PR adds the Changelg for 0.76.0-rc.0

## Changelog:
[Internal] - Add changelog for 0.76.0-rc.0

Pull Request resolved: #46419

Test Plan: N/A

Reviewed By: christophpurrer

Differential Revision: D62443133

Pulled By: cipolleschi

fbshipit-source-id: 814d1de8b90de819c60e3962430132544539bdd7