docs: update readme

Author: la3rence

README.md

@@ -7,17 +7,30 @@ export DINGTALK_TOKEN="change me"
 export DINGTALK_SECRET="change me"
 ```
 
-Test sending message:
+Test sending messages:
 
 ```shell
 go test ./... -v
 ```
 
-Send with this SDK in Go:
+Send messages with this SDK in Go:
+
+```shell
+go get -u github.com/Lonor/dingtalkbot-sdk
+```
 
 ```go
-bot := sdk.NewDingBot(os.Getenv("DINGTALK_TOKEN"), os.Getenv("DINGTALK_SECRET"))
-bot.SendSimpleText("hello world")
+package main
+
+import (
+	sdk "github.com/Lonor/dingtalkbot-sdk"
+	"os"
+)
+
+func main() {
+	bot := sdk.NewDingBot(os.Getenv("DINGTALK_TOKEN"), os.Getenv("DINGTALK_SECRET"))
+	_ = bot.SendSimpleText("hello world")
+}
 ```
 
 ## LICENSE