Add initial resources.md for discussion

The first draft of a Kubernetes resource model.
I think if a node's resource capacity is modeled like this, with capacity commonly being the only type of resource information provided, then it makes sense for a pod's resource requests/limits to be expressed the same way, with the type of information (request/limit/capacity) first, with entries for the resource names+values nested inside (like your first example).
It would be impractical/verbose to require a node's resource capacity to look like:
```
resources: [
  cpu: [ capacity: 12],
  memory: [ capacity: "128G" ],
  bananas: [ capacity: "3" ]
]
```