":include" in double quotes doesn't recognized #1587

Bug Report

Steps to reproduce

Try to embed external file using for example this link:

[readme](https://raw.githubusercontent.com/softvisio/core/main/README.md ":include")

What is current behaviour

Currently file will not be embedded, because :include tag is placed in double quotes.
This is the problem, because prettier markdown processor replaces single quotes with double and double quotes are legal for the link title.

What is the expected behaviour

I am expecting, that file will be embedded ti the parent document.

Other relevant information

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

• Your OS:

• Node.js version:

• npm/yarn version:

• Browser version:

• Docsify version: 4.12.1

• Docsify plugins:

Please create a reproducible sandbox

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