Added checkWhatsApp example

Author: Amele9

examples/checkWhatsApp/main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/green-api/whatsapp-api-client-golang/pkg/api"
+)
+
+func main() {
+	GreenAPI := api.GreenAPI{
+		IDInstance:       "1101000001",
+		APITokenInstance: "d75b3a66374942c5b3c019c698abc2067e151558acbd412345",
+	}
+
+	response, err := GreenAPI.Methods().Service().CheckWhatsapp(11001234567)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println(response)
+}