Add markdown support for arguments

[chvanam]

Pull request adding markdown support for arguments #20

• Uses spatie/laravel-markdown's blade component to render HTML tags for markdown
• The markdown HTML is styled using Tailwind's typography "prose" class, which is already present in Jetstream. Although a custom class can be used to have more control over the final styling.

Code highlighting is currently done on the client, exploring possibilities of having it on the server side instead but haven't found an easy solution yet.

[brendt]

This is great! Thank you :)