feat(example): Add missing header

Author: P-R-O-C-H-Y

libraries/Zigbee/examples/Zigbee_On_Off_MultiSwitch/Zigbee_On_Off_MultiSwitch.ino

@@ -1,3 +1,34 @@
+// Copyright 2025 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/**
+ * @brief This example demonstrates simple Zigbee multi-light switch.
+ *
+ * The example demonstrates how to use Zigbee library to control multiple light bulbs.
+ * The light bulbs are Zigbee devices, which are controlled by a Zigbee coordinator/router (Multi-Switch).
+ * Settings are stored in NVS to not be lost after power loss.
+ * Configuring and controlling the lights is done via serial input.
+ *
+ * Proper Zigbee mode must be selected in Tools->Zigbee mode
+ * and also the correct partition scheme must be selected in Tools->Partition Scheme.
+ *
+ * Please check the README.md for instructions and more detailed description.
+ *
+ * Created by Jan Procházka (https://github.com/P-R-O-C-H-Y/)
+ */
+
+
 #ifndef ZIGBEE_MODE_ZCZR
 #error "Zigbee coordinator mode is not selected in Tools->Zigbee mode"
 #endif