Documentation: How to use custom components

[aisuleep]

About this issue

There was functionality added to allow the ability to create custom components, however, (afaik) there is no documentation explaining how to use this new feature.

Request

Perhaps under the advanced usage section in the readme.md, could there be an example added of how to handle setting the regex and the component to replace the matched text with.
I am unsure if the feature allows for adding multiple custom components, or if it's limited to only customizing preexisting markdown components.

If it would be too hard to include a broad enough example to get an initial setup for adding custom components, any answers or details to the feature's usage would be greatly appreciated. Thank you for the project regardless!