Move GitHub site source into sub-directory

If this repo is going to be home to the infrastructure configuration as per #93, then I think we'll want to reorganize it so that the source of the site is one sub-directory. The infrastructure configuration can then live in another directory, and other material we need to add over time (e.g., documentation or other source code) can also find a place.

This will require a bit of work to adapt the way we are deploying the GitHub page. No one on our team has permissions to configure that currently, and it would expedite this work if either @mtelvers or myself could be given those.

We are ready to start landing pieces of documentation and the ansible configuration here, so completion of this issues should be considered blocking work at this point.

This is something we've talked about in the team, but I'd like to be sure you're onboard, @avsm.