go/asks: an ask says what a channel that proves who answers shows whole, and what Details shows (hq issue 383)

A settings proposal reached the phone with its values masked, so the operator could not
tell what they were approving. An ask now carries Whole, shown in place of Explanation on
a kind that proves its sender and carries the ask's answers, and Details, what the
Details answer shows. Both enter the digest only when given, so an ask without them
digests as before and a router and an asker of different builds still agree on it.

README.md

@@ -96,7 +96,8 @@ an event under the module's own name or kind, `stdio.SeatTake` takes a held seat
 and `stdio.SeatAnswer` carry a proof (a code typed by a person, by request and reply, never kept),
 `stdio.SeatRecord` reads a record kept for the module, and `State(...).Create` and `.Update` write by
 compare-and-set. The runtime does each only as far as the module's membership lists. `go/asks` is the
-contract on top: the `Ask` an asker publishes and the checks it is held to, the `Warrant` it acts on
+contract on top: the `Ask` an asker publishes and the checks it is held to (its `Whole` is what a channel that proves
+who answers shows in place of its `Explanation`, and its `Details` what the Details answer shows, hq issue 383), the `Warrant` it acts on
 (`For`, `Says`), and the `Message`, `Choice`, `LinkAsked` and `Code` a channel takes and says, with the
 subjects each travels on.
 `go/asker` is an asking module's client (ADR 0259 §10): `Ask` keeps an ask in the module's own state and then