RESUMABLE: Mention `Incremental: ?1`

[Acconut]

Resumable uploads work best if request content is delivered incrementally, so the partial content can be processed even if the entire request doesn't complete. We should consider recommending the inclusion of Incremental: ?1 from draft-ietf-httpbis-incremental in content-transferring requests to encourage intermediaries to not buffer.

[LPardue]

Yeah. I don't think there's much to say. We should not duplicate text for sure. However, we probably want to highlight why incremental can be useful in this use case.