Add "how we work together" docs

[mfisher87]

Should be part of the contributing docs. Link out to openscapes team culture documentation, talks, etc.

Related: #514 #525 #521

EDIT: Also #537 . I feel there's an obligation on maintainers to maintain team culture as well (not in terms of time obligations like giving presentations, but in terms of applying that culture to their other actions as maintainers) that we need to make explicit in that document, but we should probably think about these two tickets as a whole together.