chore(docs): Fix code highlighting in part 6 (#32900)

docs/docs/tutorial/part-6/index.mdx

@@ -182,9 +182,9 @@ When Gatsby builds the pages for your site, it creates routes based on the folde
 * `src/pages/index.js` still lives at the `/` route.
 * `src/pages/blog/index.js` lives at the `/blog` route.
 * `src/pages/blog/{mdx.slug}.js` gets turned into multiple routes - one for each MDX node in the data layer.
-    * Gatsby uses the MDX node with slug `my-first-post` to build a page that lives at the `blog/my-first-post route`.
-    * Gatsby uses the MDX node with slug `another-post` to build a page that lives at the `blog/another-post route`.
-    * Gatsby uses the MDX node with slug `yet-another-post` to build a page that lives at the `blog/yet-another-post route`.
+    * Gatsby uses the MDX node with slug `my-first-post` to build a page that lives at the `blog/my-first-post` route.
+    * Gatsby uses the MDX node with slug `another-post` to build a page that lives at the `blog/another-post` route.
+    * Gatsby uses the MDX node with slug `yet-another-post` to build a page that lives at the `blog/yet-another-post` route.
 
 </Collapsible>