docs(specs): align the S33 401 error row with the S08 interim

What

Aligns the S33 Error Cases 401 row with what the surface actually ships. The table promised the S01 envelope with code unauthorized, but the S08 bootstrap-token middleware answers a missing or invalid credential with an empty body and a WWW-Authenticate: Bearer challenge, on the GitLab API and the management API alike. The row now reads "none (bodiless)" and a note under the table records the interim shape and when the envelope code arrives (ADR-020's service credential, #255 (closed)).

Why

The mismatch surfaced in !1029 (merged)'s review: the OpenAPI document and the dispatch-table tests pin the bodiless 401, so every future endpoint MR on this surface would look like it violates the spec. This amendment was promised in that discussion, to land before the Step 5 endpoint MR.