Split up changes for developers (#13536)
Summary of the issue:
Parsing the "Changes for developers" is a friction point (of many) for add-on developers, and core developers.
Developers may handle deprecations, breaking changes, and other notices differently.
Description of how this pull request fixes the issue:
In future changelogs, the changes for developers should split out deprecations, and when relevant, breaking changes. This is to make parsing this as easy as possible for core and add-on developers.
Co-authored-by: Reef Turner <feerrenrut@users.noreply.github.com>
