docs(voice-call): document stale call reaper config

docs/plugins/voice-call.md

@@ -126,6 +126,35 @@ Notes:
 - `tunnel.allowNgrokFreeTierLoopbackBypass: true` allows Twilio webhooks with invalid signatures **only** when `tunnel.provider="ngrok"` and `serve.bind` is loopback (ngrok local agent). Use for local dev only.
 - Ngrok free tier URLs can change or add interstitial behavior; if `publicUrl` drifts, Twilio signatures will fail. For production, prefer a stable domain or Tailscale funnel.
 
+## Stale call reaper
+
+Use `staleCallReaperSeconds` to end calls that never receive a terminal webhook
+(for example, notify-mode calls that never complete). The default is `0`
+(disabled).
+
+Recommended ranges:
+
+- **Production:** `120`–`300` seconds for notify-style flows.
+- Keep this value **higher than `maxDurationSeconds`** so normal calls can
+  finish. A good starting point is `maxDurationSeconds + 30–60` seconds.
+
+Example:
+
+```json5
+{
+  plugins: {
+    entries: {
+      "voice-call": {
+        config: {
+          maxDurationSeconds: 300,
+          staleCallReaperSeconds: 360,
+        },
+      },
+    },
+  },
+}
+```
+
 ## Webhook Security
 
 When a proxy or tunnel sits in front of the Gateway, the plugin reconstructs the