Add initial resources.md for discussion

The first draft of a Kubernetes resource model.
I can see a use case where a pod template (see #170) would have a set limit and unset request, so that an autosizingController could adjust the request as needed.  

Not sure if podTemplates and pods need to have the same resource request.  But, on the subject of templates (#170), if pods and podTemplates are going to reuse API types with the same schema, then every field that could be in a podTemplate should be optional.