Fix typo in README.md

extra section is part of the front matter

README.md

@@ -132,11 +132,11 @@ highlight_theme = "css"
    title = "Home"
    # Note we're not setting `paginate_by` here.
    template = "section.html"
-   +++
 
    [extra]
    section_path = "blog/_index.md"  # Where to find your posts.
    max_posts = 5  # Show 5 posts on the home page.
+   +++
    ```
 
     - This will display the latest 5 posts from the `blog/` section.