add architecture document
add architecture document

There's a fair bit of network setup and accounts that exist
outside of this repository. Let's try to give an overview
that might help somebody at least know where to look to fix
something.

mosoft521/gitscm-next,Mokolea/git-scm.com,git/git-scm.com,git/git-scm.com,mosoft521/gitscm-next,git/git-scm.com,mosoft521/gitscm-next,Mokolea/git-scm.com,git/git-scm.com,mosoft521/gitscm-next,Mokolea/git-scm.com,Mokolea/git-scm.com