docs: update README to introduce the usage of opengemini-client-go

Signed-off-by: PennyYoon <[email protected]>

README.md

@@ -1,2 +1,108 @@
 # opengemini-client-go
-openGemini go client(sdk)
+opengemini-client-go is a Go client API for OpenGemini. 
+
+OpenGemini is an open-source time series database, find more about OpenGemini at https://github.com/openGemini/openGemini
+
+## Requirements
+
+- Go 1.19
+
+## Usage
+
+Import the client library:
+
+```go
+import . "github.com/openGemini/opengemini-client-go"
+```
+
+Create a Client:
+
+```go
+	config := &Config{
+		Addresses: []*Address{
+			{
+				Host: "127.0.0.1",
+				Port: 8086,
+			},
+		},
+	}
+	client, err := NewClient(config)
+	if err != nil {
+		fmt.Println(err)
+	}
+```
+
+Create a Database:
+
+```go
+	exampleDatabase := "ExampleDatabase"
+	err = client.CreateDatabase(exampleDatabase)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+```
+
+Write a single point:
+```go
+	exampleMeasurement := "ExampleMeasurement"
+	point := &Point{}
+	point.SetMeasurement(exampleMeasurement)
+	point.AddTag("Weather", "foggy")
+	p.AddField("Humidity", 87)
+	point.AddField("Temperature", 25)
+	cbFunc := func(err error) {
+		if err != nil {
+		fmt.Printf("write point failed for %s", err)
+		}
+	}
+	err = client.WritePoint(exampleDatabase, point, cbFunc)
+	if err != nil {
+		fmt.Println(err)
+	}
+```
+Write batch points:
+```go
+	exampleMeasurement := "ExampleMeasurement"
+	bp := &BatchPoints{}
+	var tagList []string
+	tagList = append(tagList, "sunny", "rainy", "windy")
+	for i := 0; i < 10; i++ {
+		p := &Point{}
+		p.SetMeasurement(exampleMeasurement)
+		p.AddTag("Weather", tagList[rand.Int31n(3)])
+		p.AddField("Humidity", rand.Int31n(100))
+		p.AddField("Temperature", rand.Int31n(40))
+		p.SetTime(time.Now())
+		bp.AddPoint(p)
+		time.Sleep(time.Nanosecond)
+	}
+	err = client.WriteBatchPoints(exampleDatabase, bp)
+	if err != nil {
+		fmt.Println(err)
+	}
+```
+
+Do a query:
+
+```go
+	q := Query{
+		Database: exampleDatabase,
+		Command:  "select * from " + exampleMeasurement,
+	}
+	res, err := client.Query(q)
+	if err != nil {
+		fmt.Println(err)
+	}
+	for _, r := range res.Results {
+		for _, s := range r.Series {
+			for _, v := range s.Values {
+				for _, i := range v {
+					fmt.Print(i)
+					fmt.Print(" | ")
+				}
+				fmt.Println()
+			}
+		}
+	}
+```