I wouldn't exactly call in definitive documentation, but in the Design Guidelines document, Section 4.7, Content Screen, the screen layout which they refer to as an "roParagraphScreen" does show a "Breadcrumb". And in section 3.2.4 Breadcrumb, it states "It should appear on all screens except the top most screen within a channel". I'm not sure if the SDK has support for breadcrumbs on ALL screens, but it at least looks like it was intended to go in the roParagraphScreen, possibly just another (of many) documentation omission.
