deploy, docs: turn service_down back on (V-444)

It was disabled because it could not say which service. It can now.

internal/config/config.go

@@ -149,10 +149,11 @@ type Config struct {
 	//
 	// Rules are code, not config (see loop.DefaultRules), and that stays true:
 	// this only subtracts. It exists because a rule can be right in principle
-	// and useless in practice — kuma's service_down cannot name the service it
-	// is nudging about (Vikunja #444), so being told "a service on homesrv is
-	// down" every fifteen minutes is noise with no action attached. Turning it
-	// off beats learning to ignore her.
+	// and useless in practice. service_down was the case that forced it: it
+	// could not name the service it was nudging about, so being told "a service
+	// on homesrv is down" every fifteen minutes was noise with no action
+	// attached. That is fixed — one fact per kuma monitor — and the rule ships
+	// enabled again. The escape hatch stays.
 	//
 	// A disabled rule is never gathered for, never evaluated, and never
 	// delivered on any channel. Unknown names are ignored, so removing a rule