Squashed 'docs_source/' changes from efbeda9..d72fa3d

d72fa3d Restructure docs.
9bcec56 the first VM is important to setup docker
f75f016 don't use "host", it's unclear
c8b8f63 add a bunch of basic instructions

git-subtree-dir: docs_source
git-subtree-split: d72fa3d7c589bb4d04048537861e0c088240cee4
Merge commit 'b19f38dfd250ad23677925ff760ba444b0aee661'
Update to docs w/ new structure.