Markdown document specification checking with slide support

[normal-coder]

Is your feature request related to a problem? Please describe.

First of all, thanks to Slidev, Markdown has been able to show its elegance in more forms!

When I'm writing Markdown, I'm also concerned with standardizing the writing so that others can better read the original Markdown. I currently use a plugin for VSCode to help me with this. Currently I follow https://github.com/DavidAnson/markdownlint

Describe the solution you'd like

Although Slidev currently provides the slidev format [entry] command to help users format, the document mentions "Note that this won't format the content of the slides, only the organization of the markdown file."

It's worth directing more attention and better habits to long lines and the use of exposed URLs, which are irregularities that affect the Markdown rendering and reading experience. That's what this Issue is about.

• Add a command like slidev check to Slidev to check for irregular writing in Markdown files.
• Providing a check without changing the content of the Slides fully preserves respect for the user's creativity, but many of Markdown's lint tools also provide the ability to try to autocorrect to the maximum extent possible without altering the original text, and perhaps providing a -force-fix capability on top of the slidev check would round out the functionality.
• Pre-populate the .markdownlint.json configuration file in the initialization scaffolding to get around IDE error messages for specifications that are allowed in the Slidev text and are not yet outside of the writing expectations.

The following are profile disabling recommendations for presets .markdownlint.json that can be used as a reference:

• MD024: Multiple headings with the same content
• MD025: Multiple top-level headings in the same document
• MD026: Trailing punctuation in heading
• MD033: Inline HTML

Describe alternatives you've considered

none.