Bug Report

The document of docsify says

A page's title tag is generated from the selected sidebar item name. For better SEO, you can customize the title by specifying a string after the filename.

<!-- docs/_sidebar.md -->
* [Home](/)
* [Guide](guide.md "The greatest guide in the world")

But when I do it, the page's title is still "Guide" rather than "The greatest guide in the world".

Steps to reproduce

Normally add files,nothing special.

What is current behaviour

The title of page is from sidebar item name.

What is the expected behaviour

customized title can work.

Other relevant information

• Bug does still occur when all/other plugins are disabled?

• Your OS: Ubuntu 16.04.7

• Node.js version: 14.7.0

• npm/yarn version: 6.14.7

• Browser version: Firefox v79.0

• Docsify version: 4.11.6

• Docsify plugins: 字数统计（docsify-count），scrollToTop

Please create a reproducible sandbox

Mention the docsify version in which this bug was not present (if any)