docs(heartbeat): add directPolicy to config examples

docs/gateway/configuration-examples.md

@@ -273,6 +273,7 @@ Save to `~/.openclaw/openclaw.json` and you can DM the bot from that number.
         every: "30m",
         model: "anthropic/claude-sonnet-4-5",
         target: "last",
+        directPolicy: "allow", // allow (default) | block
         to: "+15555550123",
         prompt: "HEARTBEAT",
         ackMaxChars: 300,

docs/gateway/heartbeat.md

@@ -32,6 +32,7 @@ Example config:
       heartbeat: {
         every: "30m",
         target: "last", // explicit delivery to last contact (default is "none")
+        directPolicy: "allow", // default: allow direct/DM targets; set "block" to suppress
         // activeHours: { start: "08:00", end: "24:00" },
         // includeReasoning: true, // optional: send separate `Reasoning:` message too
       },