Allow a Markdown file exists in more than one places in TOC while not confusing in navigation

[lilin90]

Issue description:

If a Markdown file exists in more than one places in the TOC.md file, when users click the 1st link, it jumps to the position of the 2nd place, which can be confusing to users.

Possible solution:

• Let the left navigation display the desired position according to where users click the doc page.
• Differentiate two URLs by adding /1, /2 to the end of the URL? Either via front-end or manually labeling it in TOC.md files.

[lilin90]

2025-11-25: Now the left navigation displays the desired position according to where users click the doc page.