Give every condition a headline, an explanation and a resolved line in plain words

The operator could not read the desktop notifications: they carried plan ids,
commits, keys and verb syntax. The words the operator reads now travel with the
condition, so every channel says them (hq ADR 0253).

cmd/mesh-controller/module_health.go

@@ -167,6 +167,7 @@ func judgeModuleHealth(ctx context.Context, inv *inventory.Inventory, k *conditi
 				o.Severity = conditions.Urgent
 				o.Said += "; " + waitingWords(waiters)
 				o.Summary += fmt.Sprintf("; %d consumer(s) wait on it", len(waiters))
+				o.Explanation += fmt.Sprintf(" %d module(s) that depend on it wait for it, so this is urgent.", len(waiters))
 			}
 		}
 		seen[o.Key()] = true
@@ -241,8 +242,9 @@ func sayWaiters(ctx context.Context, k *conditions.Keeper, hold *holding, p cata
 // moduleUnhealthyObservation is a module unhealthy on a machine, in words: the summary names the module,
 // the machine and what is wrong with each resource; the detail — targets, streaks, since — is evidence.
 func moduleUnhealthyObservation(module, node string, rs []inventory.ResourceHealth) conditions.Observation {
-	var words, said []string
+	var words, said, plain []string
 	for _, r := range rs {
+		plain = append(plain, resourcePlainWords(r))
 		if r.Kind == link.KindUnit {
 			// A failed unit is named by the unit, which is what a person looks for (issue 315); the
 			// resource that places it — a package, a file — is evidence.
@@ -258,8 +260,12 @@ func moduleUnhealthyObservation(module, node string, rs []inventory.ResourceHeal
 	}
 	return conditions.Observation{Scope: conditions.ScopeModule, ID: module + "." + node, Token: "unhealthy",
 		Kind: kindModuleUnhealthy, Machine: node, Severity: conditions.Warning, Source: sourceHealth,
-		Summary: fmt.Sprintf("%s on %s is not healthy: %s", module, node, strings.Join(words, "; ")),
-		Said:    strings.Join(said, "; ")}
+		Summary:  fmt.Sprintf("%s on %s is not healthy: %s", module, node, strings.Join(words, "; ")),
+		Said:     strings.Join(said, "; "),
+		Headline: fmt.Sprintf("%s not working on %s", module, node),
+		Explanation: fmt.Sprintf("%s on %s is not healthy: %s. It clears as soon as it runs again; if it stays, it "+
+			"needs a look at why it fails.", module, node, namesWords(plain, 3)),
+		Resolved: fmt.Sprintf("%s works again on %s", module, node)}
 }
 
 // reasonWords is why a resource is unhealthy, as a person reads it.