feature: Do not render Front Matter

[TimDeve]

Front Matter if often used to add metadata to Markdown documents, like in Jekyll, Gatsby or Hugo.

That Front Matter should not be rendered when rendering the Markdown document. Would it be possible to add this feature to markserv?

I see you are using markdown-it for rendering markdown, I have found this plugin to skip rendering the Front Matter, you may be able to use it to implement this feature.