Use a simple scheduled github action to deploy
the website nightly. The deploy step includes sync,
so this will pull in an up to date version of the docs
on the master branch.

With this commit we'll have the basic docs that are required for all
Tekton projects
(https://github.com/tektoncd/community/blob/master/process.md#project-requirements)
and a start at development + contributing guides, hopefully enough to
meet the requirements for #2 though we could still flesh these out
further.

Fixes #2