docs: connect go

docs/examples/go/connectexample/main.go

 package main
 
 import (
-    "database/sql"
-    "fmt"
-    "os"
+	"database/sql"
+	"fmt"
+	"os"
 
-    _ "github.com/taosdata/driver-go/v2/taosRestful"
+	_ "github.com/taosdata/driver-go/v2/taosRestful"
 )
 
 func main() {
-    dsn := os.Getenv("TDENGINE_GO_DSN")
-    taos, err := sql.Open("taosRestful", dsn)
-    if err != nil {
-        fmt.Println("failed to connect TDengine, err:", err)
-        return
-    }
-    _, err = taos.Exec("select server_version()")
-    if err != nil {
-	fmt.Println(err)
-    }
-    fmt.Println("connect success")
-    defer taos.Close()
+	dsn := os.Getenv("TDENGINE_GO_DSN")
+	taos, err := sql.Open("taosRestful", dsn)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	_, err = taos.Query("select server_version()")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	fmt.Println("connect success")
+	defer taos.Close()
 }