begin genericizing this so that editing config won't show up in git changes

[justizin]

Not sure if this is exactly the path you want to take upstream, I'm just offering to help sort of make this more generic and usable for others like me who appreciate your work.

I'm not sure off-hand if there are any other environment-specific file contents outside of site.rb, but if so I considered a script that generates them from a .json.

An interesting default solution for site.rb might also be to allow these config values to be specified by environment variables, and to make everything work with no site.rb at all.

Creating this PR mostly for discussion sake, but feel free to merge it, it's a small change which includes a documentation change.

[tmclaugh]

I'm struggling with this change and not sure what to do. I want to be able to pull this repo down anywhere and have my settings. I want people in other orgs to be able to do the same. I'm struggling with this issue right now because I forked this into my work organization and the work I've done there is totally mergeable back to here.

The larger issue is it's hard to make site specific changes in general and still keep the forked repo mergeable back here. This includes spots like scripts/ and tests/