docs: update the preview image (#460)

* docs: update the preview image

* docs:update

* update

Author: adela-bytebase

public/images/social-previews/bytebase-3-0.png

@@ -5,7 +5,7 @@ type Metadata = {
   imagePath?: string;
 };
 
-const DEFAULT_IMAGE_PATH = '/images/social-previews/index.jpg';
+const DEFAULT_IMAGE_PATH = '/images/social-previews/bytebase-3-0.png';
 
 export default function getMetadata({
   title,