Announcement regarding future of SDK

[joesus]

Checklist

• [x] I've read the Contributing Guidelines and the Code of Conduct
• [x] I've completed the Contributor License Agreement
• [x] I've ensured that all existing tests pass and added tests (when/where necessary)
• [x] I've ensured that my code lints properly: (swiftlint && swiftlint autocorrect --format)
• [x] I've updated the documentation (when/where necessary) and Changelog (when/where necessary)
• [x] I've added the proper label to this pull request (e.g. bug for bug fixes)

Pull Request Details

Outlines plan to deprecate API along with migration guide

Test Plan

N/A