Description

This PR updates the directory tree menu to display readme.md files as separate menu items that link to their parent directory.

Changes

1. Modified getAllMarkdownFiles in paths.ts to include readme.md files as separate entries in the path list with 'readme' slug.
2. Updated the DirectoryTree component to:
   • Detect readme entries by checking if the path ends with '/readme'
   • Make readme entries link to their parent directory (e.g., '/consulting/readme' links to '/consulting')
   • Keep the frontmatter title/short_title for readme files instead of hardcoding a label

Before

Directory tree would only show:

/consulting
  /child

After

Directory tree now shows:

/consulting 
  /Consulting Overview (clicking redirects to /consulting)
  /child

Where "Consulting Overview" is the frontmatter title of the readme.md file.

Testing

• Directories with readme.md files now show them as clickable items in the menu
• Clicking on the readme item correctly navigates to the parent directory
• The title shown in the menu uses the frontmatter from the readme.md file