No build reaches a machine without a gate; a release plan walks what waits (hq ADR 0236)

A send carries the machine's whole declaration, so at the switch to roll the next send of
anything would have carried the old default's backlog, unjudged, to every machine. A gated
send now carries and judges everything waiting on its machine; every other send is refused
or leaves the machine; a release plan walks what waits one machine at a time, the control
node last, and one that fails holds the next until a person releases it.

internal/catalogue/verbs.go

@@ -277,8 +277,12 @@ var ControllerVerbs = []Verb{
 			"module":   "one module",
 			"policy":   "with module: roll-out, record or default",
 			"together": "\"true\": with roll-out, every machine at once instead of one machine first",
-			"why":      "with policy: why — required for record, kept and said with the policy",
-		}, nil, "together")},
+			"why":      "with policy or release-backlog: why — required for record and for a release, kept",
+			"backlog":  "\"true\": every build waiting for a gate, per machine — what a release plan would send",
+			"release-backlog": "\"true\": release what waits now, one machine at a time, each judged — after a release " +
+				"plan failed, the mesh waits for this; with why",
+			"cause": "with release-backlog: the cause in a word (optional)",
+		}, nil, "together", "backlog", "release-backlog")},
 	{Name: "bus", Description: "The bus as a planned step (novox/hq to-be 45 §8, ADR 0236): what a bus upgrade " +
 		"would do — the bus's build on each machine against the one the mesh holds — and how the last step went. " +
 		"With upgrade, start one: a person's act with why, after the streams are snapshotted (snapshot-taken says " +