fixed file extension

Author: swsalim

src/site/_data/examples/opengraph.yaml

@@ -2,7 +2,7 @@
 title: OpenGraph
 description: Check how search engines and social medias such as Google, Facebook, Twitter display your website.
 link: 'https://www.opengraph.xyz/'
-thumbnailurl: /img/examples/opengraph.png
+thumbnailurl: /img/examples/opengraph.jpg
 tools:
   - NuxtJs
   - VueJs