updated Renaming Index section to use file name in parens instead of … (

solidjs#738)

Co-authored-by: Atila Fassina <atila@fassina.eu>

src/routes/solid-start/building-your-application/routing.mdx

@@ -81,7 +81,7 @@ To avoid this, you can rename the `index.tsx` file to the name of the folder it
 
 This way, it will be treated as the default export for that route:
 
-```jsx {2, 4, 6}
+```jsx {9}
 |-- routes/                       // example.com
     |-- blog/
         |-- article-1.tsx         // example.com/blog/article-1