Added an example of image generation using DALL-E (sashabaranov#168)

* add "name" property for ChatCompletionMessage

* added a comment to the "Name" property

* Added an example of image generation using DALL-E

---------

Co-authored-by: Contantine A <avdeev@embria.com>

README.md

@@ -170,6 +170,86 @@ func main() {
 ```
 </details>
 
+<details>
+<summary>DALL-E 2 image generation</summary>
+
+```go
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"fmt"
+	openai "github.com/sashabaranov/go-openai"
+	"image/png"
+	"os"
+)
+
+func main() {
+	c := openai.NewClient("your token")
+	ctx := context.Background()
+
+	// Sample image by link
+	reqUrl := openai.ImageRequest{
+		Prompt:         "Parrot on a skateboard performs a trick, cartoon style, natural light, high detail",
+		Size:           openai.CreateImageSize256x256,
+		ResponseFormat: openai.CreateImageResponseFormatURL,
+		N:              1,
+	}
+
+	respUrl, err := c.CreateImage(ctx, reqUrl)
+	if err != nil {
+		fmt.Printf("Image creation error: %v\n", err)
+		return
+	}
+	fmt.Println(respUrl.Data[0].URL)
+
+	// Example image as base64
+	reqBase64 := openai.ImageRequest{
+		Prompt:         "Portrait of a humanoid parrot in a classic costume, high detail, realistic light, unreal engine",
+		Size:           openai.CreateImageSize256x256,
+		ResponseFormat: openai.CreateImageResponseFormatB64JSON,
+		N:              1,
+	}
+
+	respBase64, err := c.CreateImage(ctx, reqBase64)
+	if err != nil {
+		fmt.Printf("Image creation error: %v\n", err)
+		return
+	}
+
+	imgBytes, err := base64.StdEncoding.DecodeString(respBase64.Data[0].B64JSON)
+	if err != nil {
+		fmt.Printf("Base64 decode error: %v\n", err)
+		return
+	}
+
+	r := bytes.NewReader(imgBytes)
+	imgData, err := png.Decode(r)
+	if err != nil {
+		fmt.Printf("PNG decode error: %v\n", err)
+		return
+	}
+
+	file, err := os.Create("image.png")
+	if err != nil {
+		fmt.Printf("File creation error: %v\n", err)
+		return
+	}
+	defer file.Close()
+
+	if err := png.Encode(file, imgData); err != nil {
+		fmt.Printf("PNG encode error: %v\n", err)
+		return
+	}
+
+	fmt.Println("The image was saved as example.png")
+}
+
+```
+</details>
+
 <details>
 <summary>Configuring proxy</summary>