add readme exmaple: chatgpt support context (sashabaranov#166)

Author: A11Might

README.md

@@ -271,3 +271,60 @@ c := openai.NewClientWithConfig(config)
 
 See also: https://pkg.go.dev/github.com/sashabaranov/go-openai#ClientConfig
 </details>
+
+<details>
+<summary>ChatGPT support context</summary>
+
+```go
+package main
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/sashabaranov/go-openai"
+)
+
+func main() {
+	client := openai.NewClient("your token")
+	messages := make([]openai.ChatCompletionMessage, 0)
+	reader := bufio.NewReader(os.Stdin)
+	fmt.Println("Conversation")
+	fmt.Println("---------------------")
+
+	for {
+		fmt.Print("-> ")
+		text, _ := reader.ReadString('\n')
+		// convert CRLF to LF
+		text = strings.Replace(text, "\n", "", -1)
+		messages = append(messages, openai.ChatCompletionMessage{
+			Role:    openai.ChatMessageRoleUser,
+			Content: text,
+		})
+
+		resp, err := client.CreateChatCompletion(
+			context.Background(),
+			openai.ChatCompletionRequest{
+				Model:    openai.GPT3Dot5Turbo,
+				Messages: messages,
+			},
+		)
+
+		if err != nil {
+			fmt.Printf("ChatCompletion error: %v\n", err)
+			continue
+		}
+
+		content := resp.Choices[0].Message.Content
+		messages = append(messages, openai.ChatCompletionMessage{
+			Role:    openai.ChatMessageRoleAssistant,
+			Content: content,
+		})
+		fmt.Println(content)
+	}
+}
+```
+</details>