add main.go for demo

add README.md for description

main.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"nad-plain-notifier-golang-sdk/plain"
+)
+
+func main() {
+	n := plain.Notify{
+		Notify: "test",
+		Title:  "test",
+		Device: "pc",
+	}
+
+	notifier := plain.NadNotifier{
+		Address:       "https://host:port/path",
+		SkipSSLVerify: true,
+		AccessToken:   "token",
+	}
+
+	err := notifier.Notify(&n)
+	if err != nil {
+		_ = fmt.Errorf("notify error: %v", err)
+	}
+}