✏️ Fix folder structure example on Thumbnails page

exampleSite/content/docs/thumbnails/index.md

@@ -31,13 +31,14 @@ content
 └── awesome_article.md
 ```
 
-You need to change it from a single markdown file into a folder. Create a directory with the same name of the article, inside create a `index.md` file. You'll get a structure similar to what's below. 
+You need to change it from a single Markdown file into a folder. Create a directory with the same name of the article, inside create a `index.md` file. You'll get a structure similar to what's below. 
 
 ```shell
 content
 └── awesome_article
-    └── featured.png
+    └── index.md
 ```
+
 Then you just need to add an image like explained earlier. If you want to see a sample of this, you can consult [this sample]({{< ref "thumbnail_sample" >}}).
 
 ## Hero Images