[docs] Wiki Migration: Setup Guide

[christinerogers]

Starting from the Setup Guide wiki page - https://github.com/aces/Loris/wiki/Setup --
For each step starting with 2 Project Customization :
Update both the tone and content while migrating this material to the markdown files under docs/

Guidelines to keep in mind:

• Check what's already in the docs/ markdowns first so that you'll know how they will be organized or overlap with what's already migrated.
• Follow the wiki steps on a new (non-Raisinbread) database (if you need one, let me know) and be sure to keep a Friction Log, so that what's old/confusing to others will be clear.
• For any points where you're not sure if they're still relevant, flag them in your markdown content so that the team can search for these easily
• For an example of how to update the tone, compare Install pages -- some still exist on the wiki, and most of this content was updated into markdowns last spring
• Keep verifying as you update PRs, how your markdown content looks in ReadTheDocs -- how it renders there is what really matters.
• After the pr is merged, edit the wiki page to remove the relevant content and paste a message + link to the relevant readthedocs page. (this will help us go page by page through the wiki

[christinerogers]

related to #4196