The documentations of this section is still working in progress. Before that, you can take a look at the source code directly.
Create a directory
components/ under your project root, and simply put your custom Vue components under it, then you can use it with the same name in your markdown file!
Read more in the Customization section.
Themes can provide components as well. Please read their documentations for what they have provided.
Check more in the directory structure section.