Update breaking changes to include the global CSS

Editor assessment

docs(breaking) says the breaking-changes notes are updated to include the global CSS, with two reference footers. The breaking scope is a documentation category rather than a section of the codebase, which violates scope semantics and caps the message, and the subject is otherwise imperative and unterminated. The docs type fits. No body explains the migration impact. Understandable but imprecise in scope, it is acceptable.