Add 5 Minute Quick Start guide to index page

- The current [Start guide](https://evalml.alteryx.com/en/stable/start.html) is too long for a first time user. There is too much text and information being presented to a first time user
- We need to add a "5 Minute Quick Start" guide to our Index.
- There should be a minimal amount of text, and we should quickly show the results of using EvalML
- Woodwork, and Featuretools to do this well
- https://featuretools.alteryx.com/en/stable/
- https://woodwork.alteryx.com/en/stable/
- ^ A first time is able to go to these documentation pages, and quickly understand what the library is doing