Add initial resources.md for discussion

The first draft of a Kubernetes resource model.
"a scheduler will be able to treat a pod that has a request as having an (implicit) capacity for placing containers inside it"

Can we just strike this?  It suggests that users should not be able to over-commit inside a pod, and I absolutely think they should.  I'd rather see this say something like:

Initially, resource specs for containers and nodes are supported.  We will extend this to include pods, too.  Initially the resources at a given scope bound the resources of the sum of inner scopes.  This may eventually be loosened.