add example to send message to channel

examples/send_channel_message.js

@@ -0,0 +1,27 @@
+import TCPConnection from "../src/connection/tcp_connection.js";
+import NodeJSSerialConnection from "../src/connection/nodejs_serial_connection.js";
+
+// create connection
+// const connection = new TCPConnection("10.1.0.226", 5000);
+const connection = new NodeJSSerialConnection("/dev/cu.usbmodem14401");
+
+// wait until connected
+connection.on("connected", async () => {
+
+    // we are now connected
+    console.log("Connected");
+
+    // update clock on meshcore device
+    await connection.syncDeviceTime();
+
+    // send message to channel 0
+    console.log("Sending message...");
+    await connection.sendChannelTextMessage(0, "Hello from MeshCore.js");
+
+    // disconnect
+    await connection.close();
+
+});
+
+// connect to meshcore device
+await connection.connect();