Map Markdown to HTML Documentation

[tko22]

Epic: #15
create a utility and file structure to map markdown files to the component/design documentation

So you have a list of components, which will be listed on the Sidebar (#5):

• Button
• Alert
• Text
• ....

Each Component has details on what it does/how to use it etc... This should be in a markdown file - probably like:

- content
   - design
       - typography
       - colors
       - spacing
       - .... 
   - components
       - Button
       - Alert
       - Link
       - .... 

A sidebar may have different sections, etc - do something like this https://github.com/primer/components/blob/master/docs/src/%40primer/gatsby-theme-doctocat/nav.yml

Either we can use mdx, gatsby or whatever...

[tko22]

Using mdx now...