Adding getting started page to digital.arizona.edu

[camikazegreen]

This is a work in progress, but any early thoughts and review would be appreciated!

Looking at Drupal.org's page as a comp: https://www.drupal.org/download

[michaelhagedon]

As someone just learning about the QS2 environment, I think this already provides useful context even beyond the helpful Contributing document. Even answers some questions I hadn't figured out how to articulate yet, like the role of the scaffolding repository. 👍

[smayden]

There is a typo in the word separate:

"In order to use Composer, it will need to be installed on the server hosting your website, or on seperate CI infrastructure."

[mmunro-ltrr]

Should the link on the index.html page get updated o the same PR?

[camikazegreen]

When this has enough approvals, I think that we should merge it when we are ready for pre-release.