docs: fix overview layout description to clarify TOC behavior (#1850)

Author: devin-ai-integration[bot]

fern/products/docs/pages/customization/frontmatter.mdx

@@ -236,11 +236,11 @@ Currently, relative paths are _not_ supported for this field.
 <ParamField path="layout" type="string" required={false} default="guide">
   Sets the page layout. Available options:
 
-  - `overview`: A spacious, full-width layout without a table of contents. Perfect for landing pages, section overviews, and content that benefits from maximum horizontal space. Navigation sidebar remains visible.
-  
   - `guide`: The default documentation layout featuring a table of contents on the right side. Ideal for tutorials, how-to guides, and any content that benefits from easy navigation through sections.
 
-  - `reference`: A full-width layout optimized for an API or SDK reference. Removes the table of contents so you can add another column, such as code examples. Navigation sidebar remains visible.
+  - `overview`: A wider layout (50% wider than `guide`) with a table of contents and navigation sidebar. Perfect for landing pages and section overviews that need more horizontal space while maintaining navigation.
+  
+  - `reference`: A full-width layout optimized for API or SDK reference. Always hides the table of contents so you can add another column, such as code examples. Navigation sidebar remains visible.
 
   - `page`: A distraction-free, full-screen layout that hides both the table of contents and navigation sidebar. Best for standalone content that benefits from focused reading experiences.