add msg example

README.md

@@ -1,2 +1,88 @@
 # msg
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/hslam/msg)](https://pkg.go.dev/github.com/hslam/msg)
+[![Go Report Card](https://goreportcard.com/badge/github.com/hslam/msg)](https://goreportcard.com/report/github.com/hslam/msg)
+[![LICENSE](https://img.shields.io/github/license/hslam/msg.svg?style=flat-square)](https://github.com/hslam/msg/blob/master/LICENSE)
+
 Package msg provides a way to use message queue.
+
+## Get started
+
+### Install
+```
+go get github.com/hslam/msg
+```
+### Import
+```
+import "github.com/hslam/msg"
+```
+### Usage
+#### Example
+msgsnd
+```go
+package main
+
+import (
+	"github.com/hslam/ftok"
+	"github.com/hslam/msg"
+	"time"
+)
+
+func main() {
+	key, err := ftok.Ftok("/tmp", 0x22)
+	if err != nil {
+		panic(err)
+	}
+	msgid, err := msg.Get(key, msg.IPC_CREAT|0600)
+	if err != nil {
+		panic(err)
+	}
+	defer msg.Remove(msgid)
+	m := &msg.Msg{Type: 1, Text: []byte("Hello World")}
+	err = msg.Snd(msgid, m, 0600)
+	if err != nil {
+		panic(err)
+	}
+	time.Sleep(time.Second * 10)
+}
+```
+msgrcv
+```go
+package main
+
+import (
+	"fmt"
+	"github.com/hslam/ftok"
+	"github.com/hslam/msg"
+)
+
+func main() {
+	key, err := ftok.Ftok("/tmp", 0x22)
+	if err != nil {
+		panic(err)
+	}
+	msgid, err := msg.Get(key, 0600)
+	if err != nil {
+		panic(err)
+	}
+	m := &msg.Msg{Type: 1}
+	err = msg.Rcv(msgid, m, 0600)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(string(m.Text))
+}
+```
+
+#### Output
+```
+Hello World
+```
+
+### License
+This package is licensed under a MIT license (Copyright (c) 2020 Meng Huang)
+
+
+### Author
+msg was written by Meng Huang.
+
+