[suggestion] Allow global markdown configuration

[sebovzeoueb]

I'm using this custom configuration to render some markdown in my app: md = MarkdownIt("gfm-like").use(attrs.attrs_plugin)

It would be cool if we could set this globally somewhere, for example Nuxt Content lets you set it in the main configuration file https://content.nuxt.com/get-started/configuration#markdown. Luckily I only need custom rendering in a couple of places but I can imagine setting the renderer would get tiresome in an app that needs a consistent markdown interpretation everywhere.