RESUMABLE: when appending and the offset matches the upload length, clarify what the server does

[LPardue]

During WGLC review, @MikeBishop raised the following issue as a nit on https://lists.w3.org/Archives/Public/ietf-http-wg/2025JulSep/0123.html

4.4.2: "stopping to append bytes..., rejecting the request" => "rejecting requests to append..." perhaps?

While Mike classes this as a nit, I think its a little bigger. My read is that were currently recommending that the server process the appending data up to the point the upload length is reached, then discard any data after that. Is that a right interpretation?

Think we need some editorial work here to be sure.