A silence is said on the shown message, which then times out (issue 373)

Seen at 14:40: machine.shanks.units was silenced for 7 days with a reason,
and its critical popup stood on the desk as "Still open" while the
router logged nothing. A silence now edits the message where it is shown
to "Silenced until <day>: <headline>" with the reason, no answers and no
urgency, so the desk's popup times out; nothing more is said while it
lasts. When the silence ends and the condition is still open, the message
is edited back to its open words. Resolved while silenced, it is said only
where an edit notifies nobody. The silence is taken from the controller's
event and from the 10-min reading of the open set alike.

modules/messenger/README.md

@@ -119,7 +119,7 @@ warning kept quiet is also said once after a day.
 | `condition-cleared` | once it stays cleared 2 min (10 min once it came back): its message edited to say so; said inside a digest, a line in the next one |
 | cleared and raised again before its clearing was said | nothing: to the operator it never ended — a unit failing again after each apply is one message, not one per apply; back as urgent, or with a reminder waiting when it cleared, that is said |
 | cleared, said so, and raised again within 10 min | the same message, edited back to open — not a new one (urgent: said again in its place, so it rings) |
-| silenced | nothing, its clearing included |
+| silenced | its message, where shown, edited to "Silenced until <day>: <headline>" with the reason, no answers and no urgency (the desk's popup times out); nothing more while it lasts; silence over and still open, the message is open again; resolved meanwhile, said only where an edit notifies nobody |
 
 **One message per problem** (issue 373). A record keeps the id of its message on each channel; a reminder or
 an escalation is said **in place of it** — the channel takes the earlier one away and shows the new one as a