Create Custom Components documentation section on DocsSite

[Patrick-Daly-AA]

Discussed in AlaskaAirlines/WC-Generator#528

As an Auro User
I want to better understand how to customize Auro Components
So that I can be more confident in my themeing and customizing of Auro Components

Notes:
We have sections on some of our doc site pages that mention how to customize a component, but we instead want to build a more generic page. for an example of what it looks like currently for an individual component, please see https://auro.alaskaair.com/components/auro/checkbox and scroll to the bottom.

I know I'm done when:

• Component Customization documentation has been created and added to the DocSite
• • This should be more in depth than our standard documentation pages, more akin to a walkthrough (or video) for this page.
• Clean up and remove any documentation made redundant on existing component pages