[User Script] Provide directory navigation of the markdown file content of the github website.
- The code is concise, without any third-party dependencies, to avoid affecting the page loading speed
- Generate a tree-shaped directory navigation panel with markdown file content
- The directory navigation panel can be switched to show/hide, the purpose is not to affect the normal browsing page content.
- Click the title to smoothly scroll to the target anchor point.
- The navigation bar scrolls to monitor, and the corresponding title item can be highlighted as the content scrolls.