tox: add config file

By using tox, you don't have to worry about maintaining a virtual
environment yourself with sphinx and the zerovm-sphinx-theme.
index: shorten title

The long title took up a lot of space in links on other pages.
index: split off subprojects into their own section
index: create a Zebra section

I plan to put a section about getting started before this.
contributing: add stub document about contributing
release-schedule: added stub document
contact: stub document about getting in contact
Merge pull request #7 from mgeisler/dev-process

Stub documents and proposals about our development process