Add key roatation limit to config.json

config/config.sample.json

@@ -18,6 +18,7 @@
     "membership_event_expiry_ms": 180000000,
     "delayed_leave_event_delay_ms": 18000,
     "delayed_leave_event_restart_ms": 4000,
-    "network_error_retry_ms": 100
+    "network_error_retry_ms": 100,
+    "key_rotation_participant_limit": 30
   }
 }